A194266 Smallest sum of two distinct primes of the form n*k+1.
5, 8, 20, 18, 42, 20, 72, 58, 56, 42, 90, 50, 132, 72, 92, 114, 240, 56, 420, 102, 170, 90, 186, 170, 252, 132, 272, 142, 292, 92, 684, 290, 266, 240, 282, 110, 372, 420, 236, 282, 822, 170, 604, 442, 452, 186, 942, 290, 688, 252, 410, 210, 850, 272, 992
Offset: 1
Keywords
Examples
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
Programs
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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 *)