A130616 - OEIS

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A130616

Number of triangular polyominoes (or polyiamonds) with perimeter at most n.

0, 0, 1, 2, 3, 7, 12, 28, 65, 185

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..10.

CROSSREFS

Cf. A131481 (number of n-cell polyiamonds with perimeter n+2).

Sequence in context: A203837 A342132 A032173 * A089324 A339159 A297438

Adjacent sequences: A130613 A130614 A130615 * A130617 A130618 A130619

KEYWORD

hard,more,nonn

AUTHOR

Tanya Khovanova, Aug 10 2007

EXTENSIONS

Offset corrected by John Mason, Jan 16 2023

STATUS

approved