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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
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: A003815 A306562 A351190 * A127445 A324025 A081170
KEYWORD
hard,more,nonn
AUTHOR
Tanya Khovanova, Jul 28 2007
STATUS
approved

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Last modified July 25 11:18 EDT 2024. Contains 374588 sequences. (Running on oeis4.)