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 A241920 #8 May 15 2014 10:21:54 %S A241920 1,2,3,3,4,5,5,5,6,6,7,7,7,7,8,9,9,10,10,10,11,11,11,11,11,12,12,13, %T A241920 13,13,13,13,13,14,14,14,14,15,15,15,16,17,17,17,17,17,17,17,18,18,19, %U A241920 19,19,19,19,19,19,19,20,20,20,21,21,21,21,22,22,22,22,22 %N A241920 After a(1)=1, each n appears A061395(n) times, where A061395 gives the index of the largest prime factor of n. %C A241920 Only numbers that occur just once are the powers of two (A000079). %H A241920 Antti Karttunen, <a href="/A241920/b241920.txt">Table of n, a(n) for n = 1..10081</a> %o A241920 (Scheme, with _Antti Karttunen_'s IntSeq-library) %o A241920 (define A241920 (COMPOSE-FUNS (LEAST-GTE-I 0 1 A203623) -1+)) %Y A241920 Cf. A082288, A061395, A203623, A067255, A241918, A241914, A241915. %K A241920 nonn %O A241920 1,2 %A A241920 _Antti Karttunen_, May 01 2014