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

Author

Marko Riedel, Feb 08 2022

Keywords

• nonn

Links

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

Crossrefs

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

Formula

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