A210145 a(n) = 2^n - A210109(n).

2, 4, 8, 14, 25, 41, 74, 124, 222, 390, 706, 1262, 2324, 4244, 7869, 14607, 27337, 51243, 96665, 182666, 346647, 659206, 1257287, 2402569, 4601771, 8828741, 16969511, 32665154, 62972932

Offset: 1

Author

N. J. A. Sloane, Mar 17 2012

Keywords

• nonn

Comments

This is the number of binary sequences of length n that are not 3-divided. The number that are not 2-divided turned out, surprisingly, to be A000031, so this also seems worth including.

Crossrefs

Cf. A210109, A000031, A209970.