A113968 - OEIS

A113968

a(0) = 0 and a(n) = (5*(-4)^n + 16*(-1)^n + 9*4^n)/240 for n >= 1.

0, 0, 1, 1, 15, 17, 239, 273, 3823, 4369, 61167, 69905, 978671, 1118481, 15658735, 17895697, 250539759, 286331153, 4008636143, 4581298449, 64138178287, 73300775185, 1026210852591, 1172812402961, 16419373641455, 18764998447377

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OFFSET

0,5

LINKS

Table of n, a(n) for n=0..25.

Index entries for linear recurrences with constant coefficients, signature (-1,16,16).

FORMULA

From Colin Barker, Dec 03 2012: (Start)

a(n) = (5*(-4)^n + 16*(-1)^n + 9*4^n)/240 for n>0.

G.f.: -x^2*(2*x+1) / ((x+1)*(4*x-1)*(4*x+1)). (End)

MATHEMATICA

a[n_] := If[n == 0, 1, (5(-4)^n + 16(-1)^n + 9*4^n) / 240];

a /@ Range[0, 25] (* Jean-François Alcover, Mar 30 2021 *)

CROSSREFS

Cf. A112627.

Sequence in context: A374005 A091017 A157716 * A093812 A159840 A124609

Adjacent sequences: A113965 A113966 A113967 * A113969 A113970 A113971

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, Jan 31 2006

EXTENSIONS

New name (using Colin Barker's formula) from Joerg Arndt, Aug 30 2022

STATUS

approved