A151514 Number of 1-sided snake polyominoes with n cells.

1, 1, 2, 5, 10, 24, 53, 126, 289, 686, 1604, 3792, 8925, 21051, 49638, 116858, 275480, 647573, 1525113, 3580673, 8423334, 19755938, 46422915, 108783480, 255359883, 597932342, 1402308318, 3281352516, 7689369625, 17982241557, 42108302007, 98422076879, 230322745835

Offset: 1

Author

Ed Pegg Jr, May 13 2009

Keywords

• nonn
• hard
• more

Comments

A snake polyomino has 2 cells with 1 neighbor each, and (n-2) cells with 2 neighbors each. - Arthur O'Dwyer, Dec 12 2022

Links

• Arthur O'Dwyer, Polyomino strips, snakes, and ouroboroi, Dec 10 2022.
• Ed Pegg, Jr., Illustrations of polyforms
• Eric Weisstein's World of Mathematics, Polyomino

Crossrefs

A002013 counts 2-sided (free) snake polyominoes.

A359068 gives the number of 1-sided strip polyominoes (that is, snakes without holes) with n cells; A359068(n) < A151514(n) for n >= 7.

Extensions

a(15)-a(23) from Joseph Myers, Nov 22 2010

a(24)-a(29) from Arthur O'Dwyer, Dec 10 2022

a(30)-a(33) from Arthur O'Dwyer, Jan 19 2023