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A002014
Number of symmetric filaments (strip polyominoes) with n square cells.
(Formerly M0349 N0131)
0
1, 1, 1, 2, 2, 5, 5, 12, 12, 27, 28, 64, 67, 147, 158, 348, 373, 799, 879, 1886, 2069, 4335, 4864, 10204, 11432, 23488, 26814, 55179, 62925, 127133, 147414, 298212, 345415
OFFSET
0,4
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. 310-339 in Proceedings of the Louisiana Conference on Combinatorics, Graph Theory and Computer Science. Vol. 1, edited R. C. Mullin et al., 1970.
CROSSREFS
Sequence in context: A325697 A184307 A032580 * A135153 A097896 A030223
KEYWORD
nonn
EXTENSIONS
a(23)-a(25) from Sean A. Irvine, May 21 2013
a(26)-a(32) from John Mason, Dec 05 2021
STATUS
approved