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 A290091 #5 Jul 26 2017 09:28:02 %S A290091 1,2,1,2,4,2,1,2,1,2,6,2,4,8,4,2,6,2,1,2,1,2,4,2,1,2,1,2,6,2,6,12,6,2, %T A290091 6,2,4,12,4,8,16,8,4,12,4,2,6,2,6,12,6,2,6,2,1,2,1,2,4,2,1,2,1,2,6,2, %U A290091 4,8,4,2,6,2,1,2,1,2,4,2,1,2,1,2,6,2,6,12,6,2,6,2,6,30,6,12,24,12,6,30,6,2,6,2,6,12,6,2 %N A290091 Filter based on 1-digits of base-3 expansion: a(n) = A278222(A289813(n)). %H A290091 Antti Karttunen, <a href="/A290091/b290091.txt">Table of n, a(n) for n = 0..19683</a> %o A290091 (Scheme) (define (A290091 n) (A278222 (A289813 n))) %Y A290091 Cf. A278222, A289813, A290092, A290093. %K A290091 nonn %O A290091 0,2 %A A290091 _Antti Karttunen_, Jul 25 2017