OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])]; seq={}; Do[s=usigma[n]; If[OddQ[s] || s<=2n, Continue[]]; udiv = Select[Divisors[n], GCD[ #, n/# ] == 1 &]; If[Coefficient[Times @@ (1 + x^udiv) // Expand, x, s/2] == 0, AppendTo[seq, n]], {n, 1, 1500000}]; seq
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jan 11 2019
STATUS
approved