A026950 a(n) = Sum{(k+1)*T(n,k)}, 0<=k<=n, T given by A026374.

1, 3, 10, 25, 75, 175, 500, 1125, 3125, 6875, 18750, 40625, 109375, 234375, 625000, 1328125, 3515625, 7421875, 19531250, 41015625, 107421875, 224609375, 585937500, 1220703125, 3173828125, 6591796875, 17089843750, 35400390625

Offset

0,2

Links

Table of n, a(n) for n=0..27.

Formula

(n+2)[7+3(-1)^n]/4 * 5^[(n-1)/2].

Conjecture: a(n) = 10*a(n-2)-25*a(n-4). G.f.: -(5*x^3-3*x-1)/(5*x^2-1)^2. [Colin Barker, Oct 13 2012]

Crossrefs

Sequence in context: A027227 A319748 A027228 * A095052 A196984 A131433

Adjacent sequences: A026947 A026948 A026949 * A026951 A026952 A026953

Keyword

nonn

Author

Clark Kimberling

Status

approved