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 A217426 #9 Sep 07 2014 08:39:34 %S A217426 13,4,3,3,19,29,773 %N A217426 5-adic valuation of A217425. %C A217426 A217425 consists of numbers of the form (5^r)*(7^s). This sequence holds the r values. %Y A217426 Cf. A217425, A217427. %K A217426 nonn,base,less %O A217426 1,1 %A A217426 _James G. Merickel_, Oct 03 2012