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A045631 Number of 2n-bead black-white reversible complementable strings with n black beads and fundamental period 2n. 0
1, 1, 2, 6, 20, 70, 243, 889, 3276, 12276, 46435, 176869, 677022, 2602197, 10033212, 38787495, 150286400, 583434322, 2268848988, 8836447021, 34461894010, 134564992002, 526025788992, 2058359779051, 8061905110548, 31602659997975 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..25.

FORMULA

Moebius transform of A045723 (Christian Bower).

CROSSREFS

Sequence in context: A148478 A148479 A150124 * A275046 A229472 A135413

Adjacent sequences:  A045628 A045629 A045630 * A045632 A045633 A045634

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified July 26 08:42 EDT 2021. Contains 346294 sequences. (Running on oeis4.)