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A024496 a(n) = (3/(8n-4))*C(4n,n). 0
3, 7, 33, 195, 1292, 9177, 68310, 525915, 4153380, 33460284, 273904969, 2271800037, 19050406788, 161242554550, 1375709203260, 11819200090635, 102162535941492, 887830494976788, 7752586858050900, 67986848888695660, 598522586288243760, 5287559893638230385 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..22.

FORMULA

G.f.: (g+2)*(g-1)/g^2 where g = 1+x*g^4 is the g.f. of A002293. - Mark van Hoeij, Nov 11 2011

a(n) ~ 2^(8*n - 5/2) / (sqrt(Pi) * n^(3/2) * 3^(3*n - 1/2)). - Vaclav Kotesovec, Mar 12 2019

MATHEMATICA

Table[3/(8*n - 4)*Binomial[4*n, n], {n, 1, 20}] (* Vaclav Kotesovec, Mar 12 2019 *)

PROG

(PARI) a(n) = 3*binomial(4*n, n)/(8*n-4); \\ Michel Marcus, Mar 12 2019

CROSSREFS

Cf. A005810.

Sequence in context: A057795 A054935 A208989 * A081890 A192880 A318444

Adjacent sequences:  A024493 A024494 A024495 * A024497 A024498 A024499

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

More terms from Vaclav Kotesovec, Mar 12 2019

STATUS

approved

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Last modified June 14 03:38 EDT 2021. Contains 345018 sequences. (Running on oeis4.)