A026048 (d(n)-r(n))/5, where d = A026046 and r is the periodic sequence with fundamental period (1,0,4,0,0).

15, 21, 28, 39, 52, 68, 88, 111, 140, 173, 211, 255, 304, 361, 424, 494, 572, 657, 752, 855, 967, 1089, 1220, 1363, 1516, 1680, 1856, 2043, 2244, 2457, 2683, 2923, 3176, 3445, 3728, 4026, 4340, 4669, 5016, 5379, 5759, 6157, 6572, 7007, 7460, 7932, 8424, 8935, 9468, 10021, 10595, 11191

Offset

6,1

Links

Table of n, a(n) for n=6..57.

Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,1,-3,3,-1)

Formula

a(n)=(n + 6)*(n^2 + 6*n + 38)/15 - 1/5*( 1 - 2/5*5^(1/2)*cos(2*n*Pi/5) + 2/5*2^(1/2)*(5 - 5^(1/2))^(1/2)*sin(2*n*Pi/5) + 2/5*5^(1/2)*cos(4*n*Pi/5) - 2/5*2^(1/2)*(5 + 5^(1/2))^(1/2)*sin(4*n*Pi/5)) [From Richard Choulet, Dec 14 2008]

G.f. x^6*( 15-24*x+10*x^2+3*x^3-2*x^4-14*x^5+25*x^6-11*x^7 ) / ( (x^4+x^3+x^2+x+1)*(x-1)^4 ). - R. J. Mathar, Jun 22 2013

Mathematica

LinearRecurrence[{3, -3, 1, 0, 1, -3, 3, -1}, {15, 21, 28, 39, 52, 68, 88, 111}, 60] (* Harvey P. Dale, Apr 01 2018 *)

Crossrefs

A152889 [From Richard Choulet, Dec 14 2008]

Sequence in context: A082686 A102030 A168104 * A195527 A047200 A070537

Adjacent sequences: A026045 A026046 A026047 * A026049 A026050 A026051

Keyword

nonn

Author

Clark Kimberling

Status

approved