OFFSET
2,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 2..1000
EXAMPLE
a(2) = 2 because 4 - 1 is prime; a(4) = 4 because 8*9*10-1 is prime; 12 is not in A229991 because 38*39*40 - 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 = Flatten[Position[t, 1]]
Select[Range[150], PrimeQ[Times@@Range[Prime[#]+1, Prime[#+1]-1]-1]&] (* Harvey P. Dale, Feb 15 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Oct 09 2013
STATUS
approved