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A327030
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a(n) = Sum_{d|n} phi(d)*(n/d)! for n > 0, a(0) = 0.
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2
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0, 1, 3, 8, 28, 124, 732, 5046, 40352, 362898, 3628932, 39916810, 479002388, 6227020812, 87178296258, 1307674368272, 20922789928384, 355687428096016, 6402373706092350, 121645100408832018, 2432902008180269152, 51090942171709450128, 1124000727777647596830
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OFFSET
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0,3
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COMMENTS
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LINKS
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FORMULA
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MAPLE
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with(numtheory); A327030 := n -> add(phi(d)*(n/d)!, d = divisors(n)):
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MATHEMATICA
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a[0] = 0; a[n_] := DivisorSum[n, EulerPhi[#] * (n/#)! &]; Array[a, 23, 0] (* Amiram Eldar, May 24 2021 *)
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PROG
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(PARI) a(n) = if (n>0, sumdiv(n, d, eulerphi(d)*(n/d)!), 0); \\ Michel Marcus, Aug 28 2019
(Magma) [0] cat [&+[EulerPhi(d)*Factorial(n div d):d in Divisors(n)]:n in [1..22]]; // Marius A. Burtea, Nov 13 2019
(Magma) [0] cat [&+[Factorial(Gcd(n, i)):i in [1..n]]:n in [1..22]]; // Marius A. Burtea, Nov 13 2019
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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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