0,4

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.

Table of n, a(n) for n=0..9.

Cf. A131481: a(n) is the number of n-cell polyiamonds (triangular polyominoes) with perimeter n+2.

Sequence in context: A182692 A203837 A032173 * A089324 A297438 A111759

Adjacent sequences: A130613 A130614 A130615 * A130617 A130618 A130619

hard,more,nonn

Tanya Khovanova, Aug 10 2007

approved