login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A072569 Odd interprimes. 24
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

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 *)

CROSSREFS

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

Cf. A024675, A072568.

Sequence in context: A020192 A241809 A063174 * A072572 A029708 A125215

Adjacent sequences:  A072566 A072567 A072568 * A072570 A072571 A072572

KEYWORD

nonn

AUTHOR

Marco Matosic, Jun 24 2002

EXTENSIONS

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

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 21 23:21 EST 2020. Contains 332113 sequences. (Running on oeis4.)