A351364 Number of necklaces with n black and n white beads that avoid the pattern BBBB.

1, 2, 4, 9, 21, 59, 162, 483, 1453, 4492, 14048, 44616, 142936, 462380, 1506534, 4941955, 16303783, 54066560, 180111432, 602481589, 2022797529, 6814336663, 23026359634, 78027238290, 265085903996, 902733374480, 3080967048004, 10536594982790, 36102498293396, 123920278459564

Offset

1,2

Links

Table of n, a(n) for n=1..30.

Marko R. Riedel et al., Necklaces made of black and white beads, Math StackExchange, Feb 2022.

Formula

a(n) = A003239(n) - A351363(n).

Crossrefs

Cf. A351359, A351357, A351358, A351359, A351360, A351361.

Sequence in context: A123458 A048194 A148075 * A058718 A148076 A217976

Adjacent sequences: A351361 A351362 A351363 * A351365 A351366 A351367

Keyword

nonn

Author

Marko Riedel, Feb 08 2022

Status

approved