1,1

After the missing a(9) the sequence continues: 3, 2, 1, 6, 1, 2, 3, 2, 1, 6, 1, 2, 3, 14, 1.

Table of n, a(n) for n=1..8.

Least k>0 such that 5*k^k-1 is a prime is k=2, so a(5)=2.

Cf. A000040, A193807, A231734.

Sequence in context: A209332 A020945 A231734 * A016429 A131852 A139352

Adjacent sequences: A231732 A231733 A231734 * A231736 A231737 A231738

nonn,hard,more

Alex Ratushnyak, Nov 12 2013

approved