Cat's police Dept. looking for the mices

(*

  Revision: Dec 22 2012 New age dawn! :-D

    -Minor corrections made inside the comments for clarity and readability.

  Written on my host machine:

  * 32-bit Intel Atom with 160Gb Hdd 1Gb Ram,
  * Slackware GNU Linux distro version 14
  * Free Pascal Compiler 2.6.2

*)

program a_first_half_factorial_of_terms_for_a217626;

label
  The_end;

(*

Devised and released for documentation purposes under the terms of use of
"The On-Line Encyclopedia Of Integer Sequences" (OEIS.org).

For details please visit: http://www.oeis.org


Dear user/reader:
-----------------

When it is used properly, this code should help you to find the first (B!-1) terms
of A217626, a task for which you need to have stored at least the first (B-1)! terms
of A215940. For now it is assumed that everything is done reading the numbers in base B,
and then translating such into decimal for verifying the definition of A215940 for finally
converting the results back to base B, when it is guessed that the final answers are the
terms for the base-B version of A217626.

The idea behind this processing was taken from a test session under PARI/GP like:

x=[6,0,1,2,3,4,5,7,8,9,10,11];
z=sum(y=1,12,x[y]*12^(12-y));
print(z);

This program is not expensive in lines of code and extra details such as tech checkings...
It is assumed here that you know what you are doing when messing with it, for this
subtle reason previously mentioned, this code goes without any warranty whatsoever.

*)

const
  base=13;
  faked_base=10;

type
  ptr_int64= ^int64;
  ptr_pizza= ^pizza;
  pizza= array [1..base] of int64;

const
  either_napole_or_sicilian: ptr_pizza = nil; (* PLEASE, always remember to initialize this properly!!! *)
  swissknife: ptr_int64 = nil; (* The same principle applies here *)

  (*

    Dear user,

    Sorry: You need to change properly the following two arrays when modifying base.

    My apologizes for this.

  *)

  power: pizza=
  (base*base*base*base*base*base*base*base*base*base*base*base,
   base*base*base*base*base*base*base*base*base*base*base,
   base*base*base*base*base*base*base*base*base*base,
   base*base*base*base*base*base*base*base*base,
   base*base*base*base*base*base*base*base,
   base*base*base*base*base*base*base,
   base*base*base*base*base*base,
   base*base*base*base*base,
   base*base*base*base,
   base*base*base,
   base*base,
   base,
   1);

  faked_power: pizza=
  (faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base*faked_base,
   faked_base*faked_base*faked_base,
   faked_base*faked_base,
   faked_base,
   1);

var
vbase,
vfaked_base: int64;
input_f:text;
input_s:string;
delta_A_operand,
delta_B_operand,
current,
last: int64;
register: array [1..10000] of int64;

function f(x:char):byte;
var
  ans:byte;
begin
  if (x in ['a'..'z']) then begin
    ans:=10+ord(x)-ord('a');
  end else if (x in ['0'..'9']) then begin
    ans:=ord(x)-ord('0');
  end else begin
    ans:= 255;
  end;
  f:=ans;
end;

function g(y:string):int64;
var
  ans:int64;
  k:byte;
begin
  ans:=0;
  if (length(y) = base) then for k:= 1 to base do begin
    ans:= ans + f(y[k])*either_napole_or_sicilian^[k];
  end;
  g:=ans;
end;

function p(q:longint):int64;
var
  ans:int64;
  u:longint;
begin
  ans:=1;
  if (q >= 1) then begin
     for u:= 1 to q do begin
    ans:= ans*faked_base;
     end;
  end;
  p:=ans;
end;

function h(b:longint; z:int64):int64;
var
  ans,
  cz:int64;
  k,
  w:longint;
begin
  ans:=z;
  if (b <> faked_base) then begin
    ans:=0;
    cz:=z;
    k:=1;
    while (cz >= b) do begin
      register[k]:= cz mod b;
      cz:= cz div b;
      k:=k+1;
    end;
    register[k]:=cz;
    for w:= k downto 1 do begin
      ans:= ans+register[w]*p(w-1);
    end;
  end;
  h:=ans;
end;

(*
    The filename of the data intended to be processed here should be
    passed as the first and unique parameter in the command line
    invocation to this program. The output is made directly to the
    console, so normally you should redirect it to a file in order
    to save the answer (Just a term of A217626 in each line, like
    in a b-file but without including the offsets at left)
*)

begin

  vbase:= base; (* Don't touch this!*)
  vfaked_base:= faked_base; (* Don't touch this!*)

  (* Do you want to see sparks?... disable the following enclosed block. ... It was a joke, dont do it.*)
  (* * )
  ( * *)
  if (vbase <= 10) then begin
    either_napole_or_sicilian:= @faked_power;
    swissknife:= @vfaked_base;
  end else begin
    either_napole_or_sicilian:= @power;
    swissknife:= @vbase;
  end;
  (* * )
  ( * *)

  if (paramcount() = 1) then begin
    assign(input_f, paramstr(1));
    (*$i-*)reset(input_f);(*$i+*)
    if (IOResult = 0) then begin
      readln(input_f, input_s);
      delta_A_operand:= g(input_s);
      last:=0;
      while (not eof(input_f)) do begin
    readln(input_f,input_s);
    delta_B_operand:= g(input_s);
    current:= h(swissknife^, (delta_B_operand-delta_A_operand) div (swissknife^-1) );
    writeln(current-last);
    last:= current;
      end;
    end else begin
      writeln('Unexpected error when processing: ',paramstr(1),'; **ABORTING**');
      goto The_end;
    end;
    close(input_f);
  end else begin
    writeln('You must specify one and only one filename as invocation parameter. Please try again.');
  end;
  The_end:
end.