A045630 Number of 2n-bead black-white complementable strings with n black beads and fundamental period 2n.

1, 1, 2, 9, 32, 125, 450, 1715, 6400, 24300, 92250, 352715, 1351584, 5200299, 20056582, 77558625, 300533760, 1166803109, 4537542888, 17672631899, 68923172000, 269128935495, 1052049129142, 4116715363799, 16123800483072

Offset

0,3

Comments

For n>0, a(n) is divisible by n (cf. A022553), 2*a(n) is divisible by n^2 (cf. A268619), and 12*a(n) is divisible by n^3 (cf. A268592). - Max Alekseyev, Feb 07 2016

Links

Table of n, a(n) for n=0..24.

Formula

Moebius transform of A001700(n-1). - Christian G. Bower.

For n>0, a(n) = A007727(n)/2 = n * A022553(n).

Crossrefs

Cf. A007727.

Sequence in context: A076959 A003697 A006253 * A075364 A026526 A086607

Adjacent sequences: A045627 A045628 A045629 * A045631 A045632 A045633

Keyword

nonn

Author

David W. Wilson

Status

approved