A217211 Number of binary sequences of length n with curling number 2.

0, 2, 2, 6, 12, 26, 52, 110, 214, 438, 876, 1762, 3524, 7084, 14144, 28360, 56720, 113542, 227084, 454448, 908804, 1818168, 3636336, 7273614, 14547228, 29096678, 58192994, 116390424, 232780848, 465569860, 931139720, 1862297158, 3724592874, 7449221168, 14898442336, 29796952652, 59593905304

Offset

1,2

Links

N. J. A. Sloane, Table of n, a(n) for n = 1..104 [Entries up through 51 found by direct search (see triangle A216955), later entries obtained from a recurrence.]

Crossrefs

Column 2 of A216955. Cf. A122536, A217212.

Sequence in context: A275439 A173392 A324128 * A035615 A115962 A019311

Adjacent sequences: A217208 A217209 A217210 * A217212 A217213 A217214

Keyword

nonn

Author

N. J. A. Sloane, Oct 01 2012

Extensions

a(33)-a(37) from Allan Wilks, Oct 06 2012

Status

approved