A290924 a(n) = (1/2)*A290923(n).

1, 5, 23, 104, 469, 2115, 9539, 43024, 194053, 875245, 3947651, 17805240, 80307649, 362214635, 1633710407, 7368586016, 33234813001, 149900237685, 676100727791, 3049442757256, 13754017334317, 62035266076915, 279800013602699, 1261992614249520, 5692013155802701

Offset

0,2

Links

Clark Kimberling, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (6, -8, 6, -1)

Formula

G.f.: (1 - x + x^2)/(1 - 6 x + 8 x^2 - 6 x^3 + x^4).

a(n) = 6*a(n-1) - 8*a(n-2) + 6*a(n-3) - a(n-4).

Mathematica

z = 60; s = x/(1 - x)^2; p = 1 - 2 s - 2 s^2;
Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A000027 *)
u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1]  (* A290923 *)
u/2   (* A290924 *)
LinearRecurrence[{6, -8, 6, -1}, {1, 5, 23, 104}, 30] (* Harvey P. Dale, Nov 10 2022 *)

Crossrefs

Cf. A000027, A290890.

Sequence in context: A218985 A129162 A167660 * A026760 A064914 A243873

Adjacent sequences: A290921 A290922 A290923 * A290925 A290926 A290927

Keyword

nonn,easy

Author

Clark Kimberling, Aug 19 2017

Status

approved