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A064633 a(n) = 3^n*n!*(n+2)!/2!. 1
1, 9, 216, 9720, 699840, 73483200, 10581580800, 1999918771200, 479980505088000, 142554210011136000, 51319515604008960000, 22016072194119843840000, 11096100385836401295360000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Harry J. Smith, Table of n, a(n) for n = 0..75

FORMULA

Hypergeometric generating function: (1-3*x)^(-3); a(0)=1, a(n) = n!*subs(x=0, (d^n/dx^n)(-1/((3*x-1)^3))), n=1, 2, ...

MATHEMATICA

Table[3^n n! (n+2)!/2, {n, 0, 20}] (* Harvey P. Dale, Feb 25 2015 *)

PROG

(PARI) { for (n=0, 75, write("b064633.txt", n, " ", 3^n*n!*(n + 2)!/2) ) } \\ Harry J. Smith, Sep 20 2009

CROSSREFS

Cf. A000244, A010791.

Sequence in context: A007108 A007107 A217042 * A084942 A061718 A085741

Adjacent sequences:  A064630 A064631 A064632 * A064634 A064635 A064636

KEYWORD

nonn

AUTHOR

Karol A. Penson, Oct 01 2001

STATUS

approved

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Last modified November 22 05:55 EST 2019. Contains 329388 sequences. (Running on oeis4.)