A026918 Sum{T(n-k,k)}, 0<=k<=[ n/2 ], T given by A026907.

1, 13, 41, 90, 185, 335, 601, 1020, 1729, 2857, 4721, 7710, 12593, 20459, 33241, 53880, 87337, 141421, 229001, 370650, 599921, 970823, 1571041, 2542140, 4113505, 6655945, 10769801, 17426070, 28196249, 45622667

Offset

0,2

Links

Table of n, a(n) for n=0..29.

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

Formula

8*Fibonacci(n+5) + (3/4)*[(n-1)(-1)^n - 17(n+3)]. - Ralf Stephan, May 13 2004

G.f. ( -1-12*x-25*x^2-12*x^3-x^4 ) / ( (x^2+x-1)*(x-1)^2*(1+x)^2 ). - R. J. Mathar, May 22 2013

Mathematica

LinearRecurrence[{1, 3, -2, -3, 1, 1}, {1, 13, 41, 90, 185, 335}, 30] (* Harvey P. Dale, Jan 08 2015 *)

Crossrefs

Sequence in context: A045473 A102083 A139866 * A123972 A167585 A141970

Adjacent sequences: A026915 A026916 A026917 * A026919 A026920 A026921

Keyword

nonn

Author

Clark Kimberling

Status

approved