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 A324700 #8 Mar 11 2019 20:48:35 %S A324700 0,2,4,5,8,10,11,13,16,20,22,23,25,26,31,32,37,40,43,44,46,50,52,55, %T A324700 59,62,64,65,73,74,80,83,86,88,89,92,100,101,103,104,110,115,118,121, %U A324700 124,125,128,130,131,137,143,146,148,155,160,163,166,169,172,176 %N A324700 Lexicographically earliest sequence containing 0 and all positive integers > 1 whose prime indices minus 1 already belong to the sequence. %C A324700 A self-describing sequence, similar to A304360. %C A324700 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798. %F A324700 a(n) = A324701(n) - 1. %e A324700 The sequence of terms together with their prime indices begins: %e A324700 0 %e A324700 2: {1} %e A324700 4: {1,1} %e A324700 5: {3} %e A324700 8: {1,1,1} %e A324700 10: {1,3} %e A324700 11: {5} %e A324700 13: {6} %e A324700 16: {1,1,1,1} %e A324700 20: {1,1,3} %e A324700 22: {1,5} %e A324700 23: {9} %e A324700 25: {3,3} %e A324700 26: {1,6} %e A324700 31: {11} %e A324700 32: {1,1,1,1,1} %e A324700 37: {12} %e A324700 40: {1,1,1,3} %e A324700 43: {14} %e A324700 44: {1,1,5} %t A324700 aQ[n_]:=Switch[n,0,True,1,False,_,And@@Cases[FactorInteger[n],{p_,k_}:>aQ[PrimePi[p]-1]]]; %t A324700 Select[Range[0,100],aQ] %Y A324700 Prime indices are A324701. %Y A324700 Cf. A000002, A000720, A001222, A001462, A007097, A055396, A061395, A079000, A079254, A109298, A112798, A276625, A277098, A304360. %Y A324700 Cf. A324694, A324695, A324696, A324697, A324698, A324699, A324702, A324703, A324704, A324705. %K A324700 nonn %O A324700 1,2 %A A324700 _Gus Wiseman_, Mar 10 2019