A064837 a(n) = (6*n^4 + 30*n^3 - 20*n^2 + 14)*n/30 + (n mod 2).

0, 2, 18, 114, 420, 1170, 2710, 5538, 10312, 17890, 29338, 45970, 69356, 101362, 144158, 200258, 272528, 364226, 479010, 620978, 794676, 1005138, 1257894, 1559010, 1915096, 2333346, 2821546, 3388114, 4042108, 4793266, 5652014, 6629506, 7737632, 8989058, 10397234

Offset

0,2

Links

Harry J. Smith, Table of n, a(n) for n = 0..500

G. L. Cohen and E. Tonkes, Dartboard arrangements, Elect. J. Combin., 8 (No. 2, 2001), #R4.

Index entries for linear recurrences with constant coefficients, signature (5,-9,5,5,-9,5,-1).

Formula

From R. J. Mathar, Dec 05 2008: (Start)

a(n) = 2*A064838(n).

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

a(n) = 5*a(n-1) - 9*a(n-2) + 5*a(n-3) + 5*a(n-4) - 9*a(n-5) + 5*a(n-6) - a(n-7). - Harvey P. Dale, Sep 15 2014

Mathematica

Table[(6n^4+30n^3-20n^2+14) n/30+Mod[n, 2], {n, 0, 30}] (* or *) LinearRecurrence[ {5, -9, 5, 5, -9, 5, -1}, {0, 2, 18, 114, 420, 1170, 2710}, 40] (* Harvey P. Dale, Sep 15 2014 *)

Prog

(PARI) a(n) = { (6*n^4 + 30*n^3 - 20*n^2 + 14)*n/30 + n%2 } \\ Harry J. Smith, Sep 28 2009

Crossrefs

Cf. A064838.

Sequence in context: A370732 A038721 A308700 * A224902 A027433 A153338

Adjacent sequences: A064834 A064835 A064836 * A064838 A064839 A064840

Keyword

nonn

Author

N. J. A. Sloane, Oct 25 2001

Extensions

Better description from Frank Ellermann, Mar 16 2002

Status

approved