2,1

Table of n, a(n) for n=2..6.

a(5)=10978 because 5^5^5 - 10978 is a prime and 5^5^5 - k is composite for 0<k<10978.

(PARI) a(n)=(x->x-precprime(x))(n^n^n) \\ Charles R Greathouse IV, Nov 25 2014

Cf. A103111, A074967, A074966.

Sequence in context: A089041 A059511 A112676 * A064941 A112612 A129430

Adjacent sequences: A103109 A103110 A103111 * A103113 A103114 A103115

hard,more,nonn

Farideh Firoozbakht, Mar 04 2005

a(6) from Donovan Johnson, Mar 06 2008

approved