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A093434
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a(n) = Product_{i=1..n} (2*n-i)*(2*n+i).
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1
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3, 180, 30240, 9979200, 5448643200, 4446092851200, 5068545850368000, 7694052600858624000, 15003402571674316800000, 36548288664598635724800000, 108767707065845539917004800000, 388300714225068577503707136000000
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OFFSET
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1,1
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COMMENTS
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The arithmetic mean of these numbers is 2n.
The old definition was "a(n) = product of 2n distinct numbers, n just less than 2n and n just more than 2n."
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LINKS
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FORMULA
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a(n) = (3*n)!/(2*n!).
a(n+1) = 3*(3*n+2)*(3*n+1)*a(n). (End)
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EXAMPLE
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a(3) = (3*4*5)*(7*8*9).
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MAPLE
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MATHEMATICA
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PROG
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(Magma) [Factorial(3*n)/(2*Factorial(n)): n in [1..15]]; // Vincenzo Librandi, Jan 17 2017
(PARI) for(n=1, 30, print1((3*n)!/(2*n!), ", ")) \\ G. C. Greubel, Feb 13 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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