A024874 a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (natural numbers >= 2), t = (F(2), F(3), F(4), ...).

4, 6, 19, 31, 70, 113, 223, 361, 662, 1071, 1880, 3042, 5194, 8404, 14093, 22803, 37786, 61139, 100509, 162627, 265932, 430287, 701120, 1134436, 1844096, 2983810, 4842711, 7835671, 12703934, 20555397, 33303259, 53885805, 87264322, 141196639, 228589496

Offset

2,1

Links

Table of n, a(n) for n=2..36.

Index entries for linear recurrences with constant coefficients, signature (1,3,-2,-1,-1,-3,2,1,1,1).

Formula

G.f.: x^2*(-4+x^7+x^6+2*x^5+2*x^4-2*x^3-x^2-2*x)/((x^2+x-1)*(x^4+x^2-1)^2) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 27 2009]

Mathematica

LinearRecurrence[{1, 3, -2, -1, -1, -3, 2, 1, 1, 1}, {4, 6, 19, 31, 70, 113, 223, 361, 662, 1071}, 30] (* Harvey P. Dale, Feb 03 2018 *)

Crossrefs

Sequence in context: A153777 A034189 A024697 * A095383 A116383 A026521

Adjacent sequences: A024871 A024872 A024873 * A024875 A024876 A024877

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Harvey P. Dale, Feb 03 2018

Status

approved