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A131486 a(n) is the number of triangular polyominoes (polyiamonds) with n edges. 0
0, 0, 1, 0, 1, 0, 1, 0, 3, 0, 4, 1, 11, 1, 23, 4, 62, 11, 150, 38, 411, 118, 1081, 389 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

COMMENTS

An n-celled polyiamond with perimeter p has (3n+p)/2 edges. The maximum number of edges in an n-celled polyiamond is 2n+1.

LINKS

Table of n, a(n) for n=1..24.

Isoperimetrical Polyiamonds at Poly Pages

CROSSREFS

Cf. A000577: Triangular polyominoes (or polyiamonds) with n cells. A057729: Number of triangular polyominoes (or polyiamonds) [A000577] with perimeter n. A131481: a(n) is the number of n-cell polyiamonds (triangular polyominoes) with perimeter n+2.

Sequence in context: A138376 A077140 A003815 * A127445 A081170 A201291

Adjacent sequences:  A131483 A131484 A131485 * A131487 A131488 A131489

KEYWORD

hard,more,nonn

AUTHOR

Tanya Khovanova, Jul 28 2007

STATUS

approved

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Last modified April 28 16:04 EDT 2017. Contains 285578 sequences.