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

Author

Peter Kagey, Mar 14 2020

Keywords

• nonn

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

• Code Golf Stack Exchange, Counting polystrips
• Arthur O'Dwyer, Polyomino strips, snakes, and ouroboroi, 2022.

Crossrefs

Cf. A002013.

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