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A346577
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a(n) = (1/(3*n)) * Sum_{d|n} mu(n/d) * binomial(3*d,d).
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5
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1, 2, 9, 40, 200, 1026, 5537, 30624, 173583, 1001400, 5864749, 34768296, 208267319, 1258574114, 7663720500, 46976003712, 289628805622, 1794932293950, 11175157356521, 69864074596000, 438403736543598, 2760351027094298, 17433869214973753, 110420300844952992
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OFFSET
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1,2
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COMMENTS
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Inverse Euler transform of A001764.
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LINKS
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FORMULA
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MATHEMATICA
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Table[(1/(3 n)) Sum[MoebiusMu[n/d] Binomial[3 d, d], {d, Divisors[n]}], {n, 24}]
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PROG
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(PARI) a(n) = sumdiv(n, d, moebius(n/d)*binomial(3*d, d))/(3*n); \\ Michel Marcus, Jul 24 2021
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CROSSREFS
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Cf. A001764, A005809, A008683, A022553, A060170, A082936, A346578, A346579, A346580, A346581, A346582.
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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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