A164120 Partial sums of A162396.

5, 7, 17, 21, 41, 49, 89, 105, 185, 217, 377, 441, 761, 889, 1529, 1785, 3065, 3577, 6137, 7161, 12281, 14329, 24569, 28665, 49145, 57337, 98297, 114681, 196601, 229369, 393209, 458745, 786425, 917497, 1572857, 1835001, 3145721, 3670009

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

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

Formula

a(n) = 2*a(n-2) + 7 for n > 2; a(1) = 5, a(2) = 7.

a(n) = (19 - 5*(-1)^n)*2^((2*n-1+(-1)^n)/4)/2 - 7.

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

a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3). - G. C. Greubel, Sep 12 2017

Mathematica

Rest[CoefficientList[Series[x*(5 + 2*x)/((1 - x)*(1 - 2*x^2)), {x, 0, 50}], x]] (* or *) LinearRecurrence[{1, 2, -2}, {5, 7, 17}, 50] (* G. C. Greubel, Sep 12 2017 *)

Prog

(Magma) T:=[ n le 2 select 8-3*n else 2*Self(n-2): n in [1..38] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];
(PARI) x='x+O('x^50); Vec(x*(5+2*x)/((1-x)*(1-2*x^2))) \\ G. C. Greubel, Sep 12 2017

Crossrefs

Cf. A162396, A164053 (partial sums of A162255).

Sequence in context: A331892 A331893 A331895 * A342799 A043879 A370855

Adjacent sequences: A164117 A164118 A164119 * A164121 A164122 A164123

Keyword

nonn

Author

Klaus Brockhaus, Aug 10 2009

Status

approved