A027180 a(n) = Sum_{0<=j<=i<=n} A027170(i, j).

1, 7, 27, 79, 199, 459, 1003, 2119, 4383, 8947, 18115, 36495, 73303, 146971, 294363, 589207, 1178959, 2358531, 4717747, 9436255, 18873351, 37747627, 75496267, 150993639, 301988479, 603978259, 1207957923, 2415917359, 4831836343, 9663674427, 19327350715

Offset: 0

Author

Clark Kimberling

Keywords

• nonn
• easy

Links

• Colin Barker, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (5,-9,7,-2).

Crossrefs

Partial sums of A027178.

Programs

Mathematica

LinearRecurrence[{5,-9,7,-2},{1,7,27,79},50] (* Harvey P. Dale, Jul 08 2019 *)

PARI

Vec((1+x)^2/((1-x)^3*(1-2*x)) + O(x^40)) \\ Colin Barker, Feb 20 2016

Formula

a(n) = 18*2^n - 2*n^2 - 10*n - 17.

From Colin Barker, Feb 20 2016: (Start)

a(n) = 5*a(n-1)-9*a(n-2)+7*a(n-3)-2*a(n-4) for n>3.

G.f.: (1+x)^2 / ((1-x)^3*(1-2*x)).

(End)