A111671 Smallest prime p > 3 such that p-1 has a prime factor > (p-1)^(n/(n+1)).

7, 11, 23, 47, 83, 167, 263, 563, 1187, 2063, 4127, 8423, 16487, 32843, 65543, 131267, 262643, 524387, 1048703, 2097779, 4195259, 8389163, 16777907, 33554519, 67109543, 134217827, 268436867

Offset

1,1

Comments

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.

Links

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

Crossrefs

Cf. A111668, A005385 (safe primes).

Sequence in context: A107133 A079138 A163848 * A213895 A140111 A118072

Adjacent sequences: A111668 A111669 A111670 * A111672 A111673 A111674

Keyword

nonn

Author

Rick L. Shepherd, Aug 15 2005

Status

approved