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 A217415 #9 Sep 07 2014 08:23:18 %S A217415 5,3,16,12,25,19,16,13,31,50,501 %N A217415 11-adic valuation of A217413. %C A217415 These are the exponents on 11 in numbers of the form (2^r)*(11^s) in the main sequence. %e A217415 A217413(1) = (2^71) * (11^5), so this sequence's first term is 5. %Y A217415 Cf. A217413, A217414. %K A217415 nonn,base,less %O A217415 1,1 %A A217415 _James G. Merickel_, Oct 02 2012