A027993 a(n) = 1*T(n,2n) + 2*T(n,2n-1) + ... + (2n+1)*T(n,0), T given by A027926.

1, 6, 20, 54, 132, 306, 688, 1518, 3308, 7146, 15336, 32742, 69604, 147426, 311264, 655326, 1376220, 2883546, 6029272, 12582870, 26214356, 54525906, 113246160, 234880974, 486539212, 1006632906, 2080374728, 4294967238

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (6,-13,12,-4).

Crossrefs

Cf. A047860.

Programs

Mathematica

LinearRecurrence[{6,-13,12,-4},{1,6,20,54},30] (* Harvey P. Dale, Jun 22 2018 *)

Formula

(n+5)*2^n - 2n - 4, a(0)=1. - Ralf Stephan, Mar 25 2004

G.f. ( 1-3*x^2 ) / ( (2*x-1)^2*(x-1)^2 ). - R. J. Mathar, Jun 12 2013