OFFSET
1,1
COMMENTS
Also numbers whose largest prime divisor is the smaller part of a twin prime pair. - Stefan Steinerberger, Jul 22 2006
Empirical: all terms are even numbers. - Harvey P. Dale, Sep 22 2016
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
If n=6 then the largest and the smallest distinct prime divisors are 3 and 2 and their sum is a prime.
If n=90 then the largest and the smallest distinct prime divisors are 5 and 2 and their sum is a prime.
MATHEMATICA
Select[Range[2, 500], PrimeQ[FactorInteger[ # ][[1, 1]] + FactorInteger[ # ][[ -1, 1]]] &] (* Stefan Steinerberger, Jul 22 2006 *)
pdQ[n_]:=Module[{f=FactorInteger[n][[All, 1]]}, PrimeQ[f[[1]]+f[[-1]]]]; Select[Range[2, 300], pdQ] (* Harvey P. Dale, Sep 22 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Parthasarathy Nambi, Jun 09 2006
EXTENSIONS
More terms from Stefan Steinerberger, Jul 22 2006
STATUS
approved