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 A278220 #7 Nov 19 2016 08:26:32 %S A278220 1,2,4,2,8,4,16,2,6,8,32,4,64,16,12,2,128,6,256,8,24,32,512,4,12,64,6, %T A278220 16,1024,12,2048,2,48,128,36,6,4096,256,96,8,8192,24,16384,32,12,512, %U A278220 32768,4,24,12,192,64,65536,6,72,16,384,1024,131072,12,262144,2048,24,2,144,48,524288,128,768,36,1048576,6,2097152,4096,30,256,72,96,4194304,8,6,8192 %N A278220 Filtering sequence (related to prime factorization): a(n) = A046523(A241909(n)). %H A278220 Antti Karttunen, <a href="/A278220/b278220.txt">Table of n, a(n) for n = 1..410</a> %F A278220 a(n) = A046523(A241909(n)). %F A278220 a(n) = A278219(A075158(n-1)). %o A278220 (Scheme) (define (A278220 n) (A046523 (A241909 n))) %Y A278220 Cf. A046523, A075158, A241909. %Y A278220 Cf. also A278219, A278221. %K A278220 nonn %O A278220 1,2 %A A278220 _Antti Karttunen_, Nov 16 2016