OFFSET
1,2
EXAMPLE
m=29929=173, sigma[29929]=1+173+29929=30103 and 29929-30103=-174, the 20th term here.
MATHEMATICA
ma[x_] := Part[Reverse[Flatten[FactorInteger[x]]], 2] Do[s=n-ma[DivisorSigma[1, n]]; If[Equal[Sign[s], -1], Print[s]], {n, 2, 10000000}]
PROG
(PARI) for(n=1, 1e3, if(isprime(s=sigma(n^2)), print1(n^2-s", "))) \\ Charles R Greathouse IV, Feb 19 2013
CROSSREFS
KEYWORD
sign
AUTHOR
Labos Elemer, May 15 2002
STATUS
approved