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A004993 a(n) = (6^n/n!)*Product_{k=0..n-1} (6*k + 1). 11
1, 6, 126, 3276, 93366, 2800980, 86830380, 2753763480, 88808872230, 2901089826180, 95735964263940, 3185396629145640, 106710787076378940, 3595332672265690440, 121727691903852662040, 4138741524730990509360 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..500

A. Straub, V. H. Moll, T. Amdeberhan, The p-adic valuation of k-central binomial coefficients, Acta Arith. 140 (1) (2009) 31-41, eq (1.10)

FORMULA

G.f.: (1 - 36*x)^(-1/6).

a(n) ~ Gamma(1/6)^-1*n^(-5/6)*6^(2*n)*{1 - 5/72*n^-1 - ...}. - Joe Keane (jgk(AT)jgk.org), Nov 24 2001

a(n) = (-36)^n*binomial(-1/6, n). - Peter Luschny, Oct 23 2018

MAPLE

A004993 := n -> (-36)^n*binomial(-1/6, n):

seq(A004993(n), n=0..16); # Peter Luschny, Oct 23 2018

MATHEMATICA

Table[(-36)^n Binomial[-1/6, n], {n, 0, 15}] (* Jean-Fran├žois Alcover, Jun 02 2019, after Peter Luschny *)

PROG

(PARI) vector(20, n, n--; 6^n*prod(j=0, n-1, 6*j+1)/n! ) \\ G. C. Greubel, Aug 20 2019

(MAGMA) [1] cat [6^n*(&*[6*k+1: k in [0..n-1]])/Factorial(n): n in [1..20]]; // G. C. Greubel, Aug 20 2019

(Sage) [6^(2*n)*rising_factorial(1/6, n)/factorial(n) for n in (0..20)] # G. C. Greubel, Aug 20 2019

(GAP) List([0..20], n-> 6^n*Product([0..n-1], k-> 6*k+1)/Factorial(n) ); # G. C. Greubel, Aug 20 2019

CROSSREFS

Sequence in context: A268685 A109820 A228290 * A237428 A255900 A133792

Adjacent sequences:  A004990 A004991 A004992 * A004994 A004995 A004996

KEYWORD

nonn

AUTHOR

Joe Keane (jgk(AT)jgk.org)

EXTENSIONS

Corrected by Franklin T. Adams-Watters, Oct 25 2006

STATUS

approved

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Last modified November 21 16:04 EST 2019. Contains 329371 sequences. (Running on oeis4.)