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 A027145 #7 Oct 24 2019 16:01:27 %S A027145 1,4,12,80,304,2176,8832,64768,271104,2013184,8579072,64200704, %T A027145 276815872,2082406400,9053405184,68364861440,299056168960, %U A027145 2264753766400,9954207989760,75553161871360,333336432082944,2534637351993344,11217239353065472,85421341058007040,379009013460762624 %N A027145 a(n) = A027144(2n, n). %K A027145 nonn %O A027145 0,2 %A A027145 _Clark Kimberling_ %E A027145 More terms from _Sean A. Irvine_, Oct 24 2019