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

Author

Clark Kimberling

Keywords

• nonn

Links

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

Crossrefs

A152889 [From Richard Choulet, Dec 14 2008]

Programs

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 *)

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