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 A213376 #12 Jan 30 2023 05:43:22 %S A213376 0,1,12,158,2428,37776,591729,9260272,144869916 %N A213376 Number of polyominoes of order 2n that cannot be tiled by dominoes. %F A213376 a(n) + A056785(n) = A210996(n). - _R. J. Mathar_, Jan 30 2023 %Y A213376 Cf. A056785, A056786, A213377, A213378. %K A213376 hard,more,nonn %O A213376 1,3 %A A213376 _Joseph Myers_, Jun 10 2012