A026155 T(n,n-4), where T is the array in A026148.

1, 4, 16, 56, 189, 616, 1967, 6182, 19205, 59124, 180726, 549276, 1661646, 5007520, 15042722, 45068836, 134727499, 401991436, 1197519631, 3562523314, 10585937404, 31424706800, 93206486620, 276253350360, 818278951035, 2422518642516

Offset

4,2

Links

Table of n, a(n) for n=4..29.

Formula

Conjectures from Chai Wah Wu, Mar 23 2020: (Start)

a(n) = 12*a(n-1) - 53*a(n-2) + 90*a(n-3) + 26*a(n-4) - 256*a(n-5) + 160*a(n-6) + 224*a(n-7) - 203*a(n-8) - 84*a(n-9) + 77*a(n-10) + 14*a(n-11) - 7*a(n-12) for n > 15.

G.f.: x^4*(x - 1)^2*(x^6 - 6*x^5 - 13*x^4 + 8*x^3 + 8*x^2 - 6*x + 1)/((7*x^6 + 7*x^5 - 21*x^4 + 14*x^2 - 7*x + 1)*(x^6 - 3*x^5 - 5*x^4 + 8*x^3 + 4*x^2 - 5*x + 1)). (End)

Crossrefs

First differences of A026329.

Sequence in context: A073388 A109634 A026126 * A025182 A057585 A333107

Adjacent sequences: A026152 A026153 A026154 * A026156 A026157 A026158

Keyword

nonn

Author

Clark Kimberling

Status

approved