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%I M1638 N0640 #26 Feb 02 2022 00:07:22
%S 1,2,6,19,63,216,760,2723,9880,36168,133237,492993,1829670,6804267,
%T 25336611,94416842,351989967,1312471879,4894023222,18248301701,
%U 68036380665,253638655582,945464013411,3523978989671,13133649924269
%N Number of board-pair-pile polyominoes with n cells.
%D 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.
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Vaclav Kotesovec, <a href="/A001170/b001170.txt">Table of n, a(n) for n = 1..54</a> (computed by Doron Zeilberger)
%H Moa Apagodu, <a href="https://arxiv.org/abs/math/0202295">Counting hexagonal lattice animals</a>, arXiv:math/0202295 [math.CO], 2002-2009.
%H D. Zeilberger, <a href="http://nyjm.albany.edu/j/2001/7-14p.pdf">The umbral transfer-matrix method. III. Counting animals</a>, New York J. Math 7 (2001) 223-231
%K nonn
%O 1,2
%A _N. J. A. Sloane_