OFFSET
1,2
COMMENTS
EXAMPLE
2 is in the sequence since isigma(1) + isigma(2) = 1 + 3 = 4 is divisible by 2.
MATHEMATICA
f[p_, e_] := p^(2^(-1 + Position[Reverse @ IntegerDigits[e, 2], _?(# == 1 &)])); isigma[1] = 1; isigma[n_] := Times @@ (Flatten @ (f @@@ FactorInteger[n]) + 1); seq = {}; s = 0; Do[s = s + isigma [n]; If[Divisible[s, n], AppendTo[seq, n]], {n, 1, 10^6}]; seq
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Sep 20 2019
STATUS
approved