A026053 (d(n)-r(n))/5, where d = A008778 and r is the periodic sequence with fundamental period (0,3,1,0,1).

1, 2, 5, 9, 14, 21, 29, 40, 53, 68, 86, 106, 130, 157, 187, 221, 258, 300, 346, 396, 451, 510, 575, 645, 720, 801, 887, 980, 1079, 1184, 1296, 1414, 1540, 1673, 1813, 1961, 2116, 2280, 2452, 2632, 2821, 3018, 3225, 3441, 3666, 3901, 4145, 4400, 4665, 4940, 5226, 5522, 5830, 6149, 6479, 6821

Offset: 2

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

A152892 [From Richard Choulet, Dec 14 2008]

Formula

a(n)=(n + 2)*(n^2 + 10*n + 15)/30 - 1/5*(1 + ( - 1/2 + 3/10*5^(1/2))*cos(2*n*Pi/5) + (1/5*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/10*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(2*n*Pi/5) + ( - 1/2 - 3/10*5^(1/2))*cos(4*n*Pi/5) + ( - 1/10*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/5*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(4*n*Pi/5)) [From Richard Choulet, Dec 14 2008]

a(n)= 3*a(n-1) -3*a(n-2) +a(n-3) +a(n-5) -3*a(n-6) +3*a(n-7) -a(n-8). G.f.: -x^2*(-1+x-2*x^2+x^3)/( (x^4+x^3+x^2+x+1) * (x-1)^4 ). [From R. J. Mathar, Oct 05 2009]