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A001170
Number of board-pair-pile polyominoes with n cells.
(Formerly M1638 N0640)
3
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
KEYWORD
nonn
STATUS
approved