OFFSET
1,1
EXAMPLE
a(1) = 2+3 = 5
a(2) = 3+5 = 8
a(3) = 7+13 = 20
a(4) = 5+13 = 18
a(5) = 11+31 = 42
a(6) = 7+13 = 20
MATHEMATICA
Table[ps = Select[Table[n*k + 1, {k, 100}], PrimeQ, 2]; If[Length[ps] == 2, Total[ps], 0], {n, 100}] (* T. D. Noe, Oct 21 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Sep 03 2011
STATUS
approved