OFFSET
1,1
COMMENTS
Allowing either sign in x or y leads to fractions 2^x or 2^y if x or y are negative,
but since the sum must be integer, only the case x=y=-1 matters in these quadrants. - R. J. Mathar, Jul 31 2007
MATHEMATICA
f[x_, y_]:=2^x+x*y+2^y; lst={}; Do[Do[p=f[x, y]; If[PrimeQ[p], AppendTo[lst, p]], {y, -5!, 6!}], {x, -5!, 6!}]; Take[Union[lst], 5! ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Jul 06 2009
STATUS
approved