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 A217423 #19 Sep 07 2014 08:24:29 %S A217423 47,11,34,78,16,100,94,64,10,70,175,4713 %N A217423 2-adic valuation of A217422. %C A217423 A217422 consists of numbers of the form (2^r)*(17^s). This sequence holds the r values. %Y A217423 Cf. A217422, A217424. %K A217423 nonn,base,more %O A217423 1,1 %A A217423 _James G. Merickel_, Oct 03 2012 %E A217423 a(12) added by _James G. Merickel_, Oct 07 2012