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 A027175 #7 Oct 24 2019 19:13:55 %S A027175 3,19,76,283,1046,3890,14582,55051,209062,797806,3056868,11752674, %T A027175 45316896,175175816,678639146,2634146411,10241938406,39882831446, %U A027175 155519160716,607181138846,2373227900936,9285480209456,36364319046896 %N A027175 a(n) = A027170(2n-1, n-1). %K A027175 nonn %O A027175 1,1 %A A027175 _Clark Kimberling_