1,1

a(1) = 7 = A111668(1). Conjectures: (1) This is a subsequence of the safe primes (A005385), (2) lim{n --> oo}(a(n+1)/a(n)) = 2.

Table of n, a(n) for n=1..27.

Cf. A111668, A005385 (safe primes).

Sequence in context: A079138 A319135 A163848 * A213895 A140111 A118072

Adjacent sequences: A111668 A111669 A111670 * A111672 A111673 A111674

nonn

Rick L. Shepherd, Aug 15 2005

approved