%I
%S 0,2,2,6,12,26,52,110,214,438,876,1762,3524,7084,14144,28360,56720,
%T 113542,227084,454448,908804,1818168,3636336,7273614,14547228,
%U 29096678,58192994,116390424,232780848,465569860,931139720,1862297158,3724592874,7449221168,14898442336,29796952652,59593905304
%N Number of binary sequences of length n with curling number 2.
%H N. J. A. Sloane, <a href="/A217211/b217211.txt">Table of n, a(n) for n = 1..104</a> [Entries up through 51 found by direct search (see triangle A216955), later entries obtained from a recurrence.]
%Y Column 2 of A216955. Cf. A122536, A217212.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Oct 01 2012
%E a(33)a(37) from _Allan Wilks_, Oct 06 2012
