A119381 Primes p(n) for which (p(n-1) + p(n+2)) / p(n) = 2.

37, 67, 277, 479, 613, 631, 809, 1297, 1471, 1607, 1663, 1721, 1783, 1867, 1901, 1931, 1993, 2137, 2377, 2411, 2521, 2683, 2797, 2879, 3359, 3571, 3917, 4391, 4513, 4621, 5413, 5437, 5477, 5647, 6299, 7321, 7393, 7873, 7901, 8087, 8819, 9007, 10301

Offset: 1

Author

Axel Harvey, Jul 25 2006

Keywords

• easy
• nonn

Examples

			In the ordered set of primes we have ...271,277,281,283... and (271+283)/277 = 2, therefore 277 belongs in this sequence.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A119382.

Cf. A119382.

Programs

Mathematica

Prime[Select[Range[2, 1500], (Prime[ # - 1] + Prime[ # + 2])/(Prime[ # ]) == 2 &]] (* Stefan Steinerberger, Jul 26 2006 *)
Select[Partition[Prime[Range[1300]],4,1],(#[[1]]+#[[4]])/#[[2]]==2&][[;;,2]] (* Harvey P. Dale, Aug 04 2024 *)

Formula

a(n) = Prime(A119382(n)), where Prime(n) is the n-th prime. - Stefan Steinerberger, Jul 26 2006

Extensions

More terms from Stefan Steinerberger, Jul 26 2006