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A306642
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a(n) = Sum_{k=0..n} (3*n)!/(k! * (n-k)!)^3.
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3
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1, 12, 900, 94080, 11988900, 1704214512, 260453217024, 41886697881600, 6996546610936740, 1203384096358158000, 211855235800656848400, 38011289046678107596800, 6928290032159649797280000, 1279703438754969901486464000, 239070018975087493229806080000
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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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MATHEMATICA
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Array[Sum[(3 #)!/(k!*(# - k)!)^3, {k, 0, #}] &, 15, 0] (* Michael De Vlieger, Dec 02 2021 *)
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PROG
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(PARI) {a(n) = sum(k=0, n, (3*n)!/(k!*(n-k)!)^3)}
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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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