OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..100
EXAMPLE
a(2)=56 because 1+2+7+8+14+28-4 = 56 and the subtracted divisor is square.
MATHEMATICA
aQ[n_] := (d = DivisorSigma[1, n] - 2n) > 0 && EvenQ[d] && Mod[n, d/2] == 0 && d < 2n && IntegerQ @ Sqrt[d/2]; Select[Range[10^5], aQ] (* Amiram Eldar, Sep 22 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Aug 16 2005
STATUS
approved