|
|
A348601
|
|
Nonexponential multiply-perfect numbers: numbers k such that k | A160135(k).
|
|
4
|
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
The corresponding quotients A160135(k)/k are 1, 1, 1, 1, 1, 2, 3, ...
a(8) > 1.5*10^10, if it exists.
|
|
LINKS
|
|
|
EXAMPLE
|
6 is a term since its nonexponential divisors are 1, 2 and 3, so A160135(6) = 1 + 2 + 3 = 6 which is divisible by 6.
40 is a term since its nonexponential divisors are 1, 2, 4, 5, 8 and 20, so A160135(40) = 1 + 2 + 4 + 5 + 8 + 20 = 40 which is divisible by 40.
|
|
MATHEMATICA
|
esigma[n_] := Times @@ (Sum[First[#]^d, {d, Divisors[Last[#]]}] &) /@ FactorInteger[n]; Select[Range[1000], Divisible[DivisorSigma[1, #] - esigma[#], #] &]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|