OFFSET
2,1
EXAMPLE
a(2) = 2 because 4 + 1 is prime; a(3) = 3 because 6 + 1 is prime; 4 is not in A229992 because 8*9*10 + 1 is not prime.
MATHEMATICA
q[n_] := Product[k, {k, Prime[n] + 1, Prime[n + 1] - 1}]; c[n_] := If[PrimeQ[q[n] + 1], 1, 0]; t = Table[c[n], {n, 1, 230}]; u = Rest[Flatten[Position[t, 1]]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Oct 09 2013
STATUS
approved