OFFSET
1,1
COMMENTS
MATHEMATICA
Do[f=Numerator[Sum[(-1)^(k+1)*1/2^Prime[k], {k, 1, n}]]; If[PrimeQ[f], Print[{n, f}]], {n, 1, 1000}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Aug 22 2006
STATUS
approved