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 A027150 #7 Oct 24 2019 16:04:09 %S A027150 1,1,4,6,12,20,80,152,304,528,2176,4416,8832,15488,64768,135552, %T A027150 271104,477440,2013184,4289536,8579072,15144960,64200704,138407936, %U A027150 276815872,489431040,2082406400,4526702592,9053405184,16024403968 %N A027150 a(n) = A027144(n, floor(n/2)). %K A027150 nonn %O A027150 0,3 %A A027150 _Clark Kimberling_