View difference between Paste ID: dSvtAxrr and dYeUnyR6

 /*
 This demonstrative program should be used for either documentation or instructive purposes only,
 and goes without any warranty whatsoever.
 
 This is part of: The On-Line Encyclopedia Of Integer Sequences OEIS(TM)
 
 Visit: http://www.oeis.org/A055881
 
 Author: Joerg Arndt (www.jjj.de), Dec 12 2012
 Pastebin by: R. J. Cano (remy@ula.ve), Dec 17 2012
 
 */
 
 perm(n)=
 /* Compute the first n! terms of A055881 by counting
   in rising factorial base.
   Generate all permutations of n along the way.
 */
 {
     my( fc=vector(n) ); /* mixed radix numbers (rising factorial base) */
     my( ct=0, j, a=0 );
     my( p=vector(n,k,k-1) ); /* permutation */
     my( k, t );  /* for permutations */
     while ( 1,
         print1(ct, ":  ", p); /* permutation */
         print1("  ", a );  /* A055881(ct): position of rightmost change in fc[] */
         print1("    ", fc);  /* factorial number */
         print();
         ct += 1;
 
         /* increment factorial number fc[]: */
         j = 1;
         while ( fc[j] == j,  fc[j]=0;  j+=1; );  /* scan over nines */
         if ( j==n,  return() );  /* current is last */
         fc[j] += 1;
         /* update permutation p[], reverse prefix of length j+1: */
         a = j;  /* next term of A055881 */
         j += 1;  k = 1;
         while ( k < j,
             t=p[j]; p[j]=p[k]; p[k]=t;
             k+=1; j-=1;
         );
     );
 }
 
 print("Demonstration: Reproduces the example given in the comments section for A055881");
 perm(4);
 print(" ");
 print("You are free to call perm() and experiment with it. When finished, type \"quit\" to exit.");
 print(" ");