A001170 Number of board-pair-pile polyominoes with n cells. (Formerly M1638 N0640)

1, 2, 6, 19, 63, 216, 760, 2723, 9880, 36168, 133237, 492993, 1829670, 6804267, 25336611, 94416842, 351989967, 1312471879, 4894023222, 18248301701, 68036380665, 253638655582, 945464013411, 3523978989671, 13133649924269

Offset

1,2

References

W. F. Lunnon, Counting polyominoes, pp. 347-372 of A. O. L. Atkin and B. J. Birch, editors, Computers in Number Theory. Academic Press, NY, 1971.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Vaclav Kotesovec, Table of n, a(n) for n = 1..54 (computed by Doron Zeilberger)

Moa Apagodu, Counting hexagonal lattice animals, arXiv:math/0202295 [math.CO], 2002-2009.

D. Zeilberger, The umbral transfer-matrix method. III. Counting animals, New York J. Math 7 (2001) 223-231

Crossrefs

Sequence in context: A057409 A346157 A141771 * A001168 A193111 A119255

Adjacent sequences: A001167 A001168 A001169 * A001171 A001172 A001173

Keyword

nonn

Author

N. J. A. Sloane

Status

approved