A072569 Odd interprimes.

9, 15, 21, 39, 45, 69, 81, 93, 99, 105, 111, 129, 165, 195, 205, 217, 225, 231, 279, 309, 315, 351, 363, 381, 393, 399, 405, 441, 453, 459, 465, 473, 483, 489, 495, 501, 515, 615, 625, 645, 667, 675, 687, 705, 723, 741, 747, 759, 765, 771, 803, 825, 855, 861

Offset: 1

Author

Marco Matosic, Jun 24 2002

Keywords

• nonn

Comments

The interprimes (A024675) are those integers that lie at the midpoint between consecutive odd primes.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000
• Eric Weisstein's World of Mathematics, Interprime

Crossrefs

Odd members of A024675. Sequence is union of A072572 and A072573.

Cf. A024675, A072568.

Programs

Mathematica

a = Table[ Prime[n], {n, 2, 200}]; b = {}; Do[d = (a[[n + 1]] - a[[n]])/2; If[ OddQ[ a[[n]] + d], b = Append[b, a[[n]] + d]], {n, 1, 198}]; b
Select[Plus @@@ Partition[Table[Prime[n], {n, 2, 100}], 2, 1]/2, OddQ]
Select[Mean/@Partition[Prime[Range[2,200]],2,1],OddQ] (* Harvey P. Dale, Jan 22 2019 *)

Extensions

Edited by N. J. A. Sloane and Robert G. Wilson v, Jun 27 2002