OFFSET
1,1
COMMENTS
549753192448 is also a term. - Donovan Johnson, Sep 08 2012
EXAMPLE
a(2) = 40 because 1+2+4+8+10+20-5 = 40 and the subtracted divisor is prime.
MATHEMATICA
q[n_] := (ab = DivisorSigma[1, n] - 2 n) > 0 && EvenQ[ab] && ab/2 < n && Divisible[n, ab/2] && PrimeQ[ab/2]; Select[Range[2*10^6], q] (* Amiram Eldar, Aug 05 2023 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jason Earls, Aug 13 2005
EXTENSIONS
a(15) from Donovan Johnson, Sep 27 2008
a(16)-a(17) from Donovan Johnson, Sep 08 2012
STATUS
approved