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A370054
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a(n) = 2*(3*n+1)!/(2*n+2)!.
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1
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1, 2, 14, 180, 3432, 87360, 2790720, 107442720, 4845456000, 250637587200, 14631376032000, 951675588864000, 68257101465907200, 5352223511771136000, 455529588681155788800, 41824228767217408512000, 4120692998969056333824000, 433653882272457833226240000
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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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E.g.f.: exp( 2/3 * Sum_{k>=1} binomial(3*k,k) * x^k/k ).
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PROG
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(PARI) a(n) = 2*(3*n+1)!/(2*n+2)!;
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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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