A214442 Arithmetic mean of next a(n) > 1 successive odd primes is prime.

3, 18, 3318, 39193162, 943016093, 390502539, 3

Offset: 1

Author

Alex Ratushnyak, Jul 18 2012

Keywords

• nonn
• more

Comments

Two or more primes in the arithmetic mean.

Corresponding prime arithmetic means: 5, 43, 14639, 369687067, 11370090223, 27055575571, 31756143437

Examples

			(3+5+7)/3 is prime, so a(1)=3; next (11+13+...+73+79)/18=43 is prime, so a(2)=18.
		

Crossrefs

Cf. A000040, A073684.

Programs

Mathematica

n = 1; Table[n++; s = Prime[n]; num = 1; While[num == 1 || ! PrimeQ[s/num], n++; num++; s = s + Prime[n]]; num, {3}] (* T. D. Noe, Jul 23 2012 *)