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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
OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..2000 (first 500 terms from R. H. Hardin)
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}, {1, 2, 4, 8, 14, 24, 41}, 50] (* G. C. Greubel, Sep 18 2017; amended for offset 0 by Georg Fischer, Apr 02 2019 *)
PROG
(PARI) x='x+O('x^50); Vec((1-x^5-x^6)/((1-x)*(x^4-x^3-x^2-x+1))) \\ G. C. Greubel, Sep 18 2017; amended for offset 0 by Georg Fischer, Apr 02 2019
CROSSREFS
Sequence in context: A164397 A164174 A164396 * A164405 A164163 A164395
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, Aug 14 2009
EXTENSIONS
Edited by Alois P. Heinz, Oct 11 2017
STATUS
approved