A333313 Number of 2-sided strip polyominoes with n cells and no holes.

1, 1, 1, 2, 3, 7, 13, 30, 64, 150, 338, 794, 1836, 4313, 10067, 23621, 55313, 129647, 303720, 711078, 1665037, 3894282, 9111343, 21290577, 49770844, 116206114, 271435025, 633298969, 1478178004, 3446626028, 8039424324, 18734704111, 43673728357, 101723730306

Offset

0,4

Comments

This sequence first differs from A002013 at n = 7. An example of a polyomino counted by A002013, but not by this sequence, is:

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Links

Table of n, a(n) for n=0..33.

Code Golf Stack Exchange, Counting polystrips

Arthur O'Dwyer, Polyomino strips, snakes, and ouroboroi, 2022.

Crossrefs

Cf. A002013.

Sequence in context: A113884 A070218 A048456 * A262829 A071899 A242389

Adjacent sequences: A333310 A333311 A333312 * A333314 A333315 A333316

Keyword

nonn

Author

Peter Kagey, Mar 14 2020

Extensions

a(16)-a(26) from John Mason, Sep 15 2022

a(27)-a(33) from Arthur O'Dwyer's blog added by Andrey Zabolotskiy, Jun 20 2024

Status

approved