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 A130622 #17 Jan 16 2023 15:42:25
%S A130622 0,1,2,5,11,36,122,538,2526,13166,71153,400109,2300430,13504780,
%T A130622 80547558,487327904
%N A130622 Number of polyominoes with perimeter at most 2n.
%C A130622 The perimeter of a polyomino is always even.
%C A130622 a(n) is partial sums of A057730.
%C A130622 a(n+1) >= A130866(n).
%C A130622 Is there another prime term beyond {2, 5, 11}?
%Y A130622 Cf. A131482 (number of n-celled polyominoes with perimeter 2n+2).
%Y A130622 Cf. A057730 (number of polyominoes (A000105) with perimeter 2n).
%Y A130622 Cf. A130866 (number of polyominoes with at most n cells).
%K A130622 hard,more,nonn
%O A130622 1,3
%A A130622 _Tanya Khovanova_, Aug 10 2007
%E A130622 Offset corrected by _John Mason_, Jan 16 2023
%E A130622 a(9)-a(16) from _John Mason_, Jan 16 2023