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A339686
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a(n) = Sum_{d|n} 6^(d-1).
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10
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1, 7, 37, 223, 1297, 7819, 46657, 280159, 1679653, 10078999, 60466177, 362805091, 2176782337, 13060740679, 78364165429, 470185264735, 2821109907457, 16926661132171, 101559956668417, 609359750089711, 3656158440109669, 21936950700844039, 131621703842267137
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: Sum_{k>=1} x^k / (1 - 6*x^k).
G.f.: Sum_{k>=1} 6^(k-1) * x^k / (1 - x^k).
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MATHEMATICA
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Table[Sum[6^(d - 1), {d, Divisors[n]}], {n, 1, 23}]
nmax = 23; CoefficientList[Series[Sum[x^k/(1 - 6 x^k), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
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PROG
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(PARI) a(n) = sumdiv(n, d, 6^(d-1)); \\ Michel Marcus, Dec 13 2020
(Magma)
A339686:= func< n | (&+[6^(d-1): d in Divisors(n)]) >;
(SageMath)
def A339686(n): return sum(6^(k-1) for k in (1..n) if (k).divides(n))
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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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