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A164487
Number of binary strings of length n with no substrings equal to 0001, 1010, or 1100.
1
1, 2, 4, 8, 13, 20, 30, 44, 64, 93, 135, 196, 285, 415, 605, 883, 1290, 1886, 2759, 4038, 5912, 8658, 12682, 18579, 27221, 39886, 58447, 85649, 125515, 183941, 269568, 395060, 578977, 848520, 1243554, 1822504, 2670996, 3914521, 5736995, 8407960, 12322449
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^4-x^2+x-1)/((x^3+x-1)*(x-1)^2). - R. J. Mathar, Jan 19 2011
MATHEMATICA
LinearRecurrence[{3, -3, 2, -2, 1}, {1, 2, 4, 8, 13, 20, 30}, 50] (* Harvey P. Dale, Aug 14 2023 *)
CROSSREFS
Sequence in context: A061866 A164476 A164466 * A130840 A115266 A164508
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, Aug 14 2009
EXTENSIONS
Edited by Alois P. Heinz, Oct 27 2017
STATUS
approved