A045631 Number of 2n-bead black-white reversible complementable strings with n black beads and fundamental period 2n.

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

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