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 A359523 #7 Jan 05 2023 11:05:00 %S A359523 1,2,12,51,217,846,3211 %N A359523 Number of free polyiamonds of n cells with multiply-connected interiors. %F A359523 a(n) = A070764(n) - A359524(n). %Y A359523 Cf. A000577, A070764, A359519, A359524. %K A359523 nonn,more %O A359523 12,2 %A A359523 _John Mason_, Jan 05 2023