A086518 Primes arising as the arithmetic mean of a pair of successive terms of A086517.

2, 5, 11, 13, 17, 29, 31, 23, 29, 41, 37, 41, 53, 59, 61, 53, 59, 73, 71, 73, 83, 89, 97, 101, 97, 89, 97, 109, 113, 127, 131, 137, 131, 127, 131, 127, 137, 149, 157, 163, 173, 181, 167, 157, 167, 173, 181, 191, 193, 197, 211, 223, 229, 223, 211, 223, 241, 227, 223

Offset: 1

Author

Amarnath Murthy, Jul 30 2003

Keywords

• nonn

Examples

			2 = (1+3)/2, 11 = (7+15)/2, etc.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A086517, A259602, A259603, A259604, A259605.

Programs

Haskell

a086518 n = a086518_list !! (n-1)
a086518_list = zipWith ((flip div 2 .) . (+))
                       a086517_list $ tail a086517_list
-- Reinhard Zumkeller, Jun 30 2015

PARI

v=[1]; n=1; while(n<100, s=(n+v[#v])/2; if(type(s)=="t_INT", if(isprime(s)&&!vecsearch(vecsort(v), n), print1(s,", "); v=concat(v, n); n=0)); n++) \\ Derek Orr, Jun 16 2015

Formula

a(n) = (A086517(n)+A086517(n+1))/2. - David Wasserman, Mar 10 2005

Extensions

More terms from David Wasserman, Mar 10 2005