

A002013


Filaments with n square cells.
(Formerly M0835 N0317)


9



1, 1, 1, 2, 3, 7, 13, 31, 65, 154, 347, 824, 1905, 4512, 10546, 24935, 58476, 138002, 323894, 763172, 1790585, 4213061, 9878541, 23214728, 54393063, 127687369, 298969219, 701171557, 1640683309, 3844724417, 8991137036, 21054243655, 49211076053
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OFFSET

0,4


COMMENTS

Or, number of 2sided snake polyominoes with n cells.  Ed Pegg Jr, May 13 2009


REFERENCES

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).
R. C. Tilley, R. G. Stanton and D. D. Cowan, The cell growth problem for filaments, pp. 310339 in Proceedings of the Louisiana Conference on Combinatorics, Graph Theory and Computer Science. Vol. 1, edited R. C. Mullin et al., 1970.


LINKS

Eric Weisstein's World of Mathematics, Polyomino


CROSSREFS

A333313 counts 2sided (free) "strip" polyominoes; that is, snakes with no holes.


KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



