A057729 Number of triangular polyominoes (or polyiamonds) [A000577] with perimeter n.

0, 0, 1, 1, 1, 4, 5, 16, 37, 120, 345, 1181, 3844, 13429, 46736, 167172

Offset

1,6

References

a(10) found by Brendan Owen.

Links

Table of n, a(n) for n=1..16.

Andrew Clarke, Isometrical Polyiamonds

Picture from Andrew Clarke's page showing the 4 polyiamonds of perimeter 6 and the 5 of perimeter 7.

Crossrefs

Cf. A000577, A284869, A316196.

Sequence in context: A064294 A352156 A284869 * A110278 A013628 A127007

Adjacent sequences: A057726 A057727 A057728 * A057730 A057731 A057732

Keyword

nonn,nice,more

Author

N. J. A. Sloane, Oct 29 2000

Extensions

Link updated by William Rex Marshall, Dec 16 2009

a(11)-a(12) from Luca Petrone, Apr 04 2017

a(12)-a(16) corrected and extended by John Mason, Jul 26 2021

Status

approved