A133551 Number of length n binary sequences with at most 3 of every 6 adjacent bits set.

1, 2, 4, 8, 15, 26, 42, 74, 132, 236, 421, 747, 1314, 2318, 4101, 7263, 12864, 22773, 40291, 71272, 126099, 223144, 394895, 698823, 1236609, 2188185, 3872000, 6851631, 12124307, 21454602, 37964931, 67180507, 118878510, 210360283, 372241362, 658697067

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..2000

Index entries for linear recurrences with constant coefficients, signature (1,1,0,0,1,3,0,-3,-1,0,0,-3,-1,3,0,0,0,1,0,-1).

Formula

G.f.: -(x^19 +x^18 -x^16 -x^15 -3*x^13 -2*x^12 +2*x^11 +4*x^10 +2*x^9 +x^8 +4*x^7 +4*x^6 -2*x^5 -3*x^4 -2*x^3 -x^2-x-1) / ((x-1) *(x+1) *(x^18 -3*x^12 +x^11 +x^9 +2*x^7 +3*x^6 +2*x^5 +x^3 +x -1)). - Alois P. Heinz, May 29 2020

Crossrefs

Sequence in context: A204555 A000125 A129961 * A114226 A210063 A187154

Adjacent sequences: A133548 A133549 A133550 * A133552 A133553 A133554

Keyword

nonn,easy

Author

R. H. Hardin, Dec 24 2007

Status

approved