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 A242423 #10 Sep 13 2015 07:43:44 %S A242423 3,4,7,9,10,11,12,14,15,16,17,18,19,20,23,24,26,31,32,33,34,35,37,38, %T A242423 39,41,42,43,44,45,49,50,51,52,53,54,55,56,58,59,60,61,62,63,65,66,67, %U A242423 68,69,70,71,72,74,75,77,78,79,80,81,82,83,84,87,88,89,90,92,93,94,95,96,97,98,99,100 %N A242423 Numbers in whose prime factorization the indices of primes do not sum to a triangular number. %C A242423 Numbers k such that A010054(A056239(k)) is zero, or equally, such that A002262(A056239(k)) is not zero. %C A242423 These are numbers such that any iterations of A242424 started from them lead eventually to a cycle greater than one. Please see the comments and references at A242422. %H A242423 Antti Karttunen, <a href="/A242423/b242423.txt">Table of n, a(n) for n = 1..27575</a> %e A242423 3 = p_2 is present, because 2 is not a triangular number. %e A242423 4 = p_1 * p_1 is present, because 1+1 = 2 is not a triangular number. %o A242423 (Scheme, with _Antti Karttunen_'s Intseq-library) %o A242423 (define A242423 (ZERO-POS 1 1 (COMPOSE A010054 A056239))) %Y A242423 Complement: A242422. %Y A242423 Cf. A215366, A242424, A000217, A002262, A010054, A056239. %K A242423 nonn %O A242423 1,1 %A A242423 _Antti Karttunen_, May 16 2014