A181342 a(n) = (35*n^4 - 105*n^3 + 160*n^2 - 120*n + 36)/6.

1, 26, 186, 726, 2031, 4626, 9176, 16486, 27501, 43306, 65126, 94326, 132411, 181026, 241956, 317126, 408601, 518586, 649426, 803606, 983751, 1192626, 1433136, 1708326, 2021381, 2375626, 2774526, 3221686, 3720851, 4275906

Offset: 1

Author

Klaus Brockhaus, Oct 14 2010

Keywords

• nonn
• easy

Comments

First bisection of A175898.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Crossrefs

Cf. A175898, A181343.

Programs

Magma

[ (35*n^4-105*n^3+160*n^2-120*n+36)/6: n in [1..30] ];

Mathematica

Table[(35n^4-105n^3+160n^2-120n+36)/6,{n,30}] (* or *) LinearRecurrence[ {5,-10,10,-5,1},{1,26,186,726,2031},30] (* Harvey P. Dale, Feb 19 2017 *)

PARI

a(n)=(35*n^4-105*n^3+160*n^2-120*n+36)/6 \\ Charles R Greathouse IV, Jul 06 2017

Formula

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + 140 for n > 4; a(1)=1, a(2)=26, a(3)=186, a(4)=726.

G.f.: (1 + 21*x + 66*x^2 + 46*x^3 + 6*x^4)/(1-x)^5.

a(-n+1) = A181343(n). - Bruno Berselli, Aug 23 2011