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A045630 Number of 2n-bead black-white complementable strings with n black beads and fundamental period 2n. 5
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified October 16 00:50 EDT 2018. Contains 316252 sequences. (Running on oeis4.)