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A026079 a(n) = Sum_{k = 1..n} T(k,k-1), where T is the array defined in A024996. 1
1, 3, 6, 12, 31, 83, 233, 661, 1893, 5445, 15720, 45510, 132069, 384049, 1118822, 3264644, 9539789, 27913085, 81769238, 239794424, 703906721, 2068153901, 6081507833, 17896695833, 52703944967, 155310270103, 457956633828, 1351132539606, 3988457429607 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = A025179(n) + 2, n>2.

MATHEMATICA

Join[{1, 3}, Table[Sum[ Binomial[n, 2*k]*Binomial[2*k + 1, k + 1], {k, 0, Floor[n/2]}] + 2, {n, 2, 50}]] (* G. C. Greubel, May 22 2017 *)

PROG

(PARI) concat([1, 3], for(n=2, 50, print1(2 + sum(k=0, floor(n/2), binomial(n, 2*k)*binomial(2*k+1, k+1)), ", "))) \\ G. C. Greubel, May 22 2017

CROSSREFS

Cf. A025179.

Sequence in context: A219634 A252696 A288147 * A066710 A033648 A102972

Adjacent sequences:  A026076 A026077 A026078 * A026080 A026081 A026082

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified October 19 03:10 EDT 2021. Contains 348073 sequences. (Running on oeis4.)