This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A137929 #9 Apr 09 2014 10:14:06
%S A137929 2,3,4,5,7,10,8,9,11,12,13,14,16,15,18,17,19,20,23,21,22,24,25,26,27,
%T A137929 28,29,30,31,33,32,37,34,35,36,38,41,39,40,42,43,44,47,45,46,48,49,50,
%U A137929 53,51,52,54,59,55,56,57,58,60,61,62,64,63,65,67,66,68,71
%N A137929 If n = the k-th prime power (including 1), then a(n) = the (k+1)th prime power. If n = the k-th positive integer that is not a prime power, then a(n) = the (k+1)th positive integer that is not a prime power.
%C A137929 This is a permutation of the positive integers excluding 1 and 6.
%o A137929 (PARI) ispp(n) = (n==1) || isprimepower(n);
%o A137929 lista(nn) = {vn = vector(nn, i, i); vpp = select(n->ispp(n), vn); vnpp = select(n->(!ispp(n)), vn); vr = vector(nn); for (i=1, #vpp-1, vr[vpp[i]] = vpp[i+1];); for (i=1, #vnpp-1, vr[vnpp[i]] = vnpp[i+1];); for (i=1, nn, if (vr[i], print1(vr[i], ", "), return()););} \\ _Michel Marcus_, Feb 10 2014
%Y A137929 Cf. A000961, A024619.
%K A137929 nonn
%O A137929 1,1
%A A137929 _Leroy Quet_, Apr 30 2008
%E A137929 More terms from _Michel Marcus_, Feb 10 2014