OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
a(2)=10 because 10 has only one pair of prime factors (2 and 5) and 10 + 2 + 5 = 17, which is prime.
MATHEMATICA
ptpQ[n_]:=Module[{fi=FactorInteger[n]}, Length[fi]==2&&Union[ fi[[All, 2]]] == {1}&&PrimeQ[n+Total[fi[[All, 1]]]]]; Select[Range[400], ptpQ] (* Harvey P. Dale, Nov 06 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Chuck Seggelin (barkeep(AT)plastereddragon.com), Oct 11 2003
STATUS
approved