A066876 Numbers n such that prime(k+2) + prime(k-2) = 2*prime(k).

5, 6, 7, 27, 28, 36, 41, 54, 80, 82, 94, 126, 127, 131, 160, 177, 236, 248, 287, 339, 362, 385, 387, 400, 401, 410, 432, 433, 477, 485, 566, 579, 580, 581, 586, 599, 689, 700, 735, 744, 793, 821, 863, 874, 954, 1031, 1043, 1069, 1081, 1113, 1143, 1145, 1193

Offset

1,1

Comments

If (prime(k+2) + prime(k-2))/prime(k) is an integer, then it can only be 2.

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[3, 1200], Prime[ # ] == (Prime[ # + 2] + Prime[ # - 2])/2 &] (* Ray Chandler, Jan 09 2007 *)
Flatten[Position[Partition[Prime[Range[1200]], 5, 1], _?(#[[1]]+#[[5]] == 2#[[3]]&), 1, Heads->False]]+2 (* Harvey P. Dale, Jan 01 2022 *)

Prog

(PARI) isok(k) = { k > 2 && prime(k+2) + prime(k-2) == 2*prime(k) } \\ Harry J. Smith, Apr 03 2010

Crossrefs

Sequence in context: A273402 A217295 A272676 * A048042 A048090 A048027

Adjacent sequences: A066873 A066874 A066875 * A066877 A066878 A066879

Keyword

nonn

Author

Benoit Cloitre, Jan 21 2002

Extensions

Corrected and extended by Ray Chandler, Jan 09 2007

Status

approved