1,1

Average of n and n-th prime is a prime. All n must be odd.

Paolo P. Lava, Table of n, a(n) for n = 1..1000

15 is in the list since (15+Prime(15))/2=31.

Select[Range[632], PrimeQ[(# + Prime[#])/2] &]

Cf. A000040.

Sequence in context: A217406 A181664 A224535 * A329184 A077349 A257020

Adjacent sequences: A225858 A225859 A225860 * A225862 A225863 A225864

nonn

Jayanta Basu, May 18 2013

approved