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A327412
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a(n) = multinomial(3*n+2; 2, 3, 3, ..., 3) (n times '3').
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3
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1, 10, 560, 92400, 33633600, 22870848000, 26072766720000, 46174869861120000, 120054661638912000000, 438679733628584448000000, 2175851478797778862080000000, 14240947928731462652313600000000, 120136636726778618934917529600000000, 1280656547507460077846220865536000000000
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = 2^(-n-1)*3^(-n)*Gamma(3*n + 3).
a(n) = (9*(n-1)^3 + 36*(n-1)^2 + 47*n - 27)*a(n-1)/2 for n > 0.
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MAPLE
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a:= n-> combinat[multinomial](3*n+2, 3$n, 2):
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PROG
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(SageMath)
def a(n): return multinomial([2] + [3] * n)
[a(n) for n in range(15)]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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