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A026955 a(n) = Sum_{k=0..n} (k+1) * T(n,k), with T given by A026386. 0
1, 3, 8, 25, 60, 175, 400, 1125, 2500, 6875, 15000, 40625, 87500, 234375, 500000, 1328125, 2812500, 7421875, 15625000, 41015625, 85937500, 224609375, 468750000, 1220703125, 2539062500, 6591796875, 13671875000, 35400390625 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

For n>0, a(n) = (n+2)[7-3(-1)^n]/10 * 5^[n/2].

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

CROSSREFS

Sequence in context: A076049 A026970 A026980 * A093900 A018789 A203413

Adjacent sequences:  A026952 A026953 A026954 * A026956 A026957 A026958

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified December 2 08:31 EST 2021. Contains 349437 sequences. (Running on oeis4.)