OFFSET
1,4
COMMENTS
a(n) = 1 iff (prime(n))^2 + prime(n) - 1 is prime (A053184).
LINKS
Peter J. C. Moses, Table of n, a(n) for n = 1..400
MATHEMATICA
Table[(div=Most[Divisors[n+1]]; Length[FixedPoint[Union[Flatten[AppendTo[div, Map[Most[Rest[Divisors[n+#]]]&, #]]]]&, div]]-1), {n, Prime[Range[40]]^2-1}] (* Peter J. C. Moses, Jun 20 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Jun 19 2013
EXTENSIONS
More terms from Peter J. C. Moses, Jun 20 2013
STATUS
approved