OFFSET
1,1
COMMENTS
Observation: it seems that the prime divisors of a majority of numbers n are of the form {2, p, q} with q = 2^4 + p^4, but there exists more rarely odd numbers with more prime divisors (example from Michel Marcus: 3955413 = 3*7*11*17123).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1500
EXAMPLE
582 is in the sequence because the prime divisors of 582 are 2, 3 and 97 => 2^4 + 3^4 = 97.
MATHEMATICA
fpdQ[n_]:=Module[{f=Transpose[FactorInteger[n]][[1]]}, Max[f]-Total[Most[f]^4]==0]; Union[Select[Range[2, 5*10^5], fpdQ]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jun 26 2014
STATUS
approved