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Number of symmetric filaments (strip polyominoes) with n square cells.
(Formerly M0349 N0131)
0

%I M0349 N0131 #20 Feb 04 2022 00:36:47

%S 1,1,1,2,2,5,5,12,12,27,28,64,67,147,158,348,373,799,879,1886,2069,

%T 4335,4864,10204,11432,23488,26814,55179,62925,127133,147414,298212,

%U 345415

%N Number of symmetric filaments (strip polyominoes) with n square cells.

%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).

%D 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.

%K nonn

%O 0,4

%A _N. J. A. Sloane_

%E a(23)-a(25) from _Sean A. Irvine_, May 21 2013

%E a(26)-a(32) from _John Mason_, Dec 05 2021