Number of necklaces with n black and n white beads with at least four consecutive black beads.

A351363

Number of necklaces with n black and n white beads with at least four consecutive black beads.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =5a(5) =21a(6) =84a(7) =327a(8) =1251a(9) =4760a(10) =18018a(11) =68104a(12) =257088a(13) =970480a(14) =3664070a(15) =13842215a(16) =52331695a(17) =198021936a(18) =750027090a(19) =2843686271a(20) =10792866315a(21) =41006110365a(22) =155961264880a(23) =593797895358

External references