1,1

A065507[n] is the smallest prime q such that (p^q+1)/(p+1) is a prime, where p = Prime(n).

Table of n, a(n) for n=1..4.

A065507[n] begins {3, 3, 5, 3, 5, 3, 7, 17, 11, 7, 109, 5, 17, 5, 5, 21943, 17,...}.

Thus

a(1) = 5 because A065507[5] = 5,

a(2) = 7 because A065507[7] = 7,

a(3) = 17 because A065507[17] = 17.

Cf. A065507.

Sequence in context: A079604 A101580 A190663 * A248480 A243844 A271656

Adjacent sequences: A123192 A123193 A123194 * A123196 A123197 A123198

hard,more,nonn

Alexander Adamchuk, Oct 04 2006

approved