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 A265898 #9 Dec 25 2015 21:04:28 %S A265898 0,1,3,6,8,11,14,17,20,27,34,41,45,49,81,85,89,102,106,115,124,128, %T A265898 137,142,146,151,160,169,174,188,193,202,207,212,231,236,241,246,251, %U A265898 256,306,311,316,321,326,331,336,357,362,367,383,388,393,409,414,425,430,446,462,478,489,494,505,516,521,532,543,554,565 %N A265898 Numbers n for which (2n)! / n! [= A001813(n)] is >= k! but < 2*k! for some k; positions of ones in A265894. %C A265898 a(0) = 0 is a special case in this sequence, thus the indexing starts from zero. %C A265898 Numbers n such that A001813(n) is in A265334. %H A265898 Antti Karttunen, <a href="/A265898/b265898.txt">Table of n, a(n) for n = 0..843</a> %Y A265898 After zero-term, a subsequence of A265899. %Y A265898 Cf. A001813, A265894, A265334. %Y A265898 Cf. also A265897. %K A265898 nonn %O A265898 0,3 %A A265898 _Antti Karttunen_, Dec 24 2015