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%I #19 Mar 26 2023 10:27:24
%S 3,36,720,16128,380160,9225216,228114432,5715394560,144599482368,
%T 3685869158400,94513444945920,2435255516528640,62999001405849600,
%U 1635260233414606848,42568679092062781440,1110895735754245275648
%N a(n) = 3*2^(2*n)*(3*n)!/((2*n)!*n!).
%D W. A. Whitworth, DCC Exercises in Choice and Chance, Stechert, NY, 1945, p. 35.
%H Delbert L. Johnson, <a href="/A006587/b006587.txt">Table of n, a(n) for n = 0..699</a>
%H M. Le Brun, <a href="/A006577/a006577.pdf">Email to N. J. A. Sloane, Jul 1991</a>
%p A006587:=n->3*2^(2*n)*(3*n)!/((2*n)!*n!); seq(A006587(n), n=0..50); # _Wesley Ivan Hurt_, Nov 23 2013
%t Table[3*2^(2n)(3n)!/((2n)!*n!), {n, 0, 50}] (* _Wesley Ivan Hurt_, Nov 23 2013 *)
%o (PARI) a(n)=3*binomial(3*n,n)*4^n \\ _Charles R Greathouse IV_, Aug 11 2017
%K nonn
%O 0,1
%A _N. J. A. Sloane_
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