1,2

Theorem (Artur Jasinski): zero does not occur in this sequence. Proof: (p-1)^2-1=(p-2)p. This means that p is greatest prime divisor of (p-1)^2-1 for every p.

a(2)-a(25)=total number of terms in A181447-A181470.

Table of n, a(n) for n=1..25.

Cf. A175607, A175901-A175904, A181447-A181470.

Sequence in context: A312805 A312806 A036693 * A272753 A272804 A237990

Adjacent sequences: A181468 A181469 A181470 * A181472 A181473 A181474

more,nonn

Artur Jasinski, Oct 21 2010, Oct 22 2010.

approved