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A164400 Number of binary strings of length n with no substrings equal to 0001 or 1100. 1
1, 2, 4, 8, 14, 24, 41, 70, 120, 206, 354, 609, 1048, 1804, 3106, 5348, 9209, 15858, 27308, 47026, 80982, 139457, 240156, 413568, 712198, 1226464, 2112073, 3637166, 6263504, 10786278, 18574874, 31987489, 55085136, 94861220, 163358970, 281317836, 484452889 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..2000 (first 500 terms from R. H. Hardin)

Index entries for linear recurrences with constant coefficients, signature (2,0,0,-2,1).

FORMULA

G.f.: (x^6+x^5-1)/((x-1)*(x^4-x^3-x^2-x+1)). - R. J. Mathar, Nov 28 2011

MATHEMATICA

LinearRecurrence[{2, 0, 0, -2, 1}, {14, 24, 41, 70, 120}, 50] (* G. C. Greubel, Sep 18 2017 *)

PROG

(PARI) x='x+O('x^50); Vec(x^4*(14-4*x-7*x^2-12*x^3+8*x^4)/((1-x)*(x^4-x^3-x^2-x+1))) \\ G. C. Greubel, Sep 18 2017

CROSSREFS

Sequence in context: A178982 A164397 A164174 * A164163 A164160 A164171

Adjacent sequences:  A164397 A164398 A164399 * A164401 A164402 A164403

KEYWORD

nonn,easy

AUTHOR

R. H. Hardin, Aug 14 2009

EXTENSIONS

Edited by Alois P. Heinz, Oct 11 2017

STATUS

approved

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Last modified November 20 08:12 EST 2017. Contains 294962 sequences.