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A026950 a(n) = Sum{(k+1)*T(n,k)}, 0<=k<=n, T given by A026374. 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 20 12:38 EST 2019. Contains 320327 sequences. (Running on oeis4.)