A026917 a(n) = Sum{T(i,j)}, 0<=j<=i, 0<=i<=n, T given by A026907.

1, 27, 127, 399, 1039, 2439, 5383, 11439, 23743, 48567, 98455, 198495, 398863, 799911, 1602343, 3207567, 6418399, 12840471, 25685047, 51374655, 102754351, 205514247, 411034567, 822075759, 1644158719, 3288325239, 6576658903, 13153326879, 26306663503

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).

Programs

Mathematica

LinearRecurrence[{5,-9,7,-2},{1,27,127,399},30] (* Harvey P. Dale, Jul 03 2017 *)

PARI

Vec((1+22*x+x^2)/((1-x)^3*(1-2*x)) + O(x^40)) \\ Colin Barker, Feb 18 2016

Formula

a(n) = 98*2^n - 12*n^2 - 60*n - 97.

From Colin Barker, Feb 18 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+22*x+x^2) / ((1-x)^3*(1-2*x)).

(End)