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A162573 Primes of the form 2^x+x*y+2^y, with x and y integers of any sign. 4
2, 3, 5, 13, 17, 89, 137, 157, 257, 523, 547, 2089, 2659, 4217, 8821, 16553, 34981, 65537, 65761, 262433, 524309, 524353, 524971, 2097223, 2097289, 2097427, 2099431, 8390909, 10486243, 35652109, 134217757, 536871089, 536873279 (list; graph; refs; listen; history; text; internal format)
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

LINKS

Table of n, a(n) for n=1..33.

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

Sequence in context: A108562 A087523 A073919 * A087356 A281598 A042261

Adjacent sequences:  A162570 A162571 A162572 * A162574 A162575 A162576

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jul 06 2009

STATUS

approved

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Last modified August 7 15:08 EDT 2020. Contains 336276 sequences. (Running on oeis4.)