A211966 Number of binary sequences of length 2n and curling number 1.

2, 6, 20, 74, 286, 1124, 4460, 17768, 70930, 283440, 1133200, 4531686, 18124522, 72493652, 289965744, 1159845258, 4639345612, 18557311624, 74229104872, 296916136278, 1187663978718, 4750654782144, 19002616863186, 76010462922018

Offset: 1

Author

Omar E. Pol, Nov 28 2012

Keywords

• nonn

Comments

Equivalently, number of binary sequences of length 2n with no initial repeats (see A122536).

Links

• B. Chaffin, J. P. Linderman, N. J. A. Sloane and Allan Wilks, On Curling Numbers of Integer Sequences, arXiv:1212.6102
• B. Chaffin, J. P. Linderman, N. J. A. Sloane and Allan Wilks, On Curling Numbers of Integer Sequences, Journal of Integer Sequences, Vol. 16 (2013), Article 13.4.3.
• Index entries for sequences related to curling numbers

Crossrefs

Bisection of A122536.

Cf. A093371, A211965, A216955, A216958.

Formula

a(n) = 2*A093371(2n) = A093371(2n+1) = A211965(n+1)/2.