A026047 a(n) = (d(n)-r(n))/2, where d = A026046 and r is the periodic sequence with fundamental period (0,1,0,1).

38, 52, 72, 97, 130, 170, 220, 279, 350, 432, 528, 637, 762, 902, 1060, 1235, 1430, 1644, 1880, 2137, 2418, 2722, 3052, 3407, 3790, 4200, 4640, 5109, 5610, 6142, 6708, 7307, 7942, 8612, 9320, 10065, 10850, 11674, 12540, 13447, 14398, 15392, 16432, 17517, 18650, 19830, 21060, 22339, 23670

Offset

6,1

Links

Table of n, a(n) for n=6..54.

Index entries for linear recurrences with constant coefficients, signature (3,-2,-2,3,-1).

Formula

a(n)=(n + 6)*(n^2 + 6*n + 38)/6 - 0.5*sin(n*Pi/2)^2 [From Richard Choulet, Dec 13 2008]

G.f. x^6*( 38-62*x-8*x^2+61*x^3-27*x^4 ) / ( (1+x)*(x-1)^4 ). - R. J. Mathar, Jun 22 2013

Crossrefs

Sequence in context: A078539 A282813 A125970 * A039352 A043175 A043955

Adjacent sequences: A026044 A026045 A026046 * A026048 A026049 A026050

Keyword

nonn

Author

Clark Kimberling

Status

approved