1,2

n=1:p(2)+p(1)=3+2=5 n=2:p(3)+p(2)=5+3=8; n=18:p(19)+p(18)=61+67=128; n=564:p(565)+p(564)=4099+4093=8192; no more found below n=10^7.

Do[s=Prime[n+1]+Prime[n]; If[Equal[Length[FactorInteger[s]], 1], Print[{n, Prime[n], s}]], {n, 1, 10000000}]

p = q = 2; NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; Do[q = NextPrim[p]; If[ Length[ Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[p + q]]] == 1, Print[n]]; p = q, {n, 1, 10^7}] (from Robert G. Wilson v Jan 24 2004)

Cf. A091624.

Sequence in context: A015203 A121936 A063389 this_sequence A013035 A132520 A131631

Adjacent sequences: A071349 A071350 A071351 this_sequence A071353 A071354 A071355

more,nonn

Labos E. (labos(AT)ana.sote.hu), May 21 2002