A317781 Number of binary words of length n containing exactly two (possibly overlapping) occurrences of the subword 01101.

1, 4, 13, 35, 92, 230, 562, 1333, 3106, 7114, 16090, 35968, 79637, 174812, 380903, 824469, 1774122, 3797436, 8089574, 17158409, 36250415, 76309260, 160102335, 334877607, 698461293, 1452964434, 3015112497, 6242510786, 12896941964, 26591579894, 54724833014

Offset

8,2

Links

Alois P. Heinz, Table of n, a(n) for n = 8..2000

Index entries for linear recurrences with constant coefficients, signature (6,-12,5,18,-39,33,6,-42,47,-21,-9,20,-15,6,-1).

Formula

G.f.: x^8*(x-1)^2/(x^5-2*x^4+x^3-2*x+1)^3.

Crossrefs

Column k=2 of A277751.

Sequence in context: A177155 A189595 A189602 * A271358 A306349 A268996

Adjacent sequences: A317778 A317779 A317780 * A317782 A317783 A317784

Keyword

nonn,easy

Author

Alois P. Heinz, Aug 06 2018

Status

approved