A173248 a(0)=1, a(n) = (-1)^n*(n^3-15*n^2-12+2*n)/6, n>0.

-1, 4, -10, 19, -30, 42, -54, 65, -74, 80, -82, 79, -70, 54, -30, -3, 46, -100, 166, -245, 338, -446, 570, -711, 870, -1048, 1246, -1465, 1706, -1970, 2258, -2571, 2910, -3276, 3670, -4093, 4546, -5030, 5546, -6095, 6678, -7296, 7950, -8641, 9370

Offset

0,2

Comments

Limiting ratio a(n+1)/a(n) is near -1.071806167400881 as n->infinity.

Links

Table of n, a(n) for n=0..44.

Index entries for linear recurrences with constant coefficients, signature (-4, -6, -4, -1).

Formula

G.f.: (x^4 - x^3 - 1)/(x + 1)^4.

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

Mathematica

p[x_] = (x^4 - x^3 - 1)/(x + 1)^4;
a = Table[SeriesCoefficient[ Series[p[x], {x, 0, 50}], n], {n, 0, 50}]
LinearRecurrence[{-4, -6, -4, -1}, {-1, 4, -10, 19, -30}, 50] (* Harvey P. Dale, Nov 21 2019 *)

Crossrefs

Cf. A089071, A105811

Sequence in context: A348239 A062198 A050858 * A267882 A238705 A022785

Adjacent sequences: A173245 A173246 A173247 * A173249 A173250 A173251

Keyword

sign,easy

Author

Roger L. Bagula, Feb 13 2010

Extensions

Definition simplified by the Assoc. Editors of the OEIS, Feb 21 2010

Status

approved