A164444 Number of binary strings of length n with no substrings equal to 0000 1001 or 1011.

13, 21, 32, 48, 72, 109, 165, 250, 378, 572, 865, 1309, 1980, 2996, 4532, 6857, 10373, 15694, 23742, 35920, 54341, 82213, 124376, 188168, 284672, 430677, 651557, 985730, 1491282, 2256132, 3413241, 5163821, 7812212, 11818924, 17880556, 27051089

Offset

4,1

Links

R. H. Hardin, Table of n, a(n) for n=4..500

Index entries for linear recurrences with constant coefficients, signature (1,1,-1,1).

Formula

G.f.: -x^4*(13+8*x-2*x^2+8*x^3) / ( -1+x+x^2-x^3+x^4 ). - R. J. Mathar, Jan 19 2011

Mathematica

LinearRecurrence[{1, 1, -1, 1}, {13, 21, 32, 48}, 40] (* Harvey P. Dale, Sep 11 2017 *)

Crossrefs

Sequence in context: A020440 A164458 A164452 * A164438 A164490 A164460

Adjacent sequences: A164441 A164442 A164443 * A164445 A164446 A164447

Keyword

nonn,easy

Author

R. H. Hardin, Aug 14 2009

Status

approved