A015240 a(n) = (2*n - 5)n^2.

0, -3, -4, 9, 48, 125, 252, 441, 704, 1053, 1500, 2057, 2736, 3549, 4508, 5625, 6912, 8381, 10044, 11913, 14000, 16317, 18876, 21689, 24768, 28125, 31772, 35721, 39984, 44573, 49500, 54777, 60416, 66429

Offset: 0

Author

N. J. A. Sloane, Dec 11 1999

Keywords

• sign
• easy

Links

• Ivan Panchenko, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Programs

Mathematica

Table[(2*n - 5)n^2, {n,0,25}] (* or *) LinearRecurrence[{4,-6,4,-1},{0, -3, -4, 9},25] (* G. C. Greubel, Jul 30 2016 *)

PARI

a(n)=(2*n-5)*n^2 \\ Charles R Greathouse IV, Jul 30 2016

Formula

G.f.: x*(-3 + 8*x + 7*x^2)/(1-x)^4. - Ivan Panchenko, Nov 09 2013

From G. C. Greubel, Jul 30 2016: (Start)

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4).

E.g.f.: x*(-3 + x + 2*x^2)*exp(x). (End)