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 A130616 #7 Jan 16 2023 09:02:51 %S A130616 0,0,1,2,3,7,12,28,65,185 %N A130616 Number of triangular polyominoes (or polyiamonds) with perimeter at most n. %C A130616 Partial sums of A057729 - Number of triangular polyominoes (or polyiamonds) with perimeter n. a(n+2) >= A130867(n) - Triangular polyominoes (or polyiamonds) with n cells at most. %Y A130616 Cf. A131481 (number of n-cell polyiamonds with perimeter n+2). %K A130616 hard,more,nonn %O A130616 1,4 %A A130616 _Tanya Khovanova_, Aug 10 2007 %E A130616 Offset corrected by _John Mason_, Jan 16 2023