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A072571
Even interprimes i = (p+q)/2 (where p, q are consecutive primes) such that (q-p)/2 is divisible by 3.
3
26, 34, 50, 56, 64, 76, 86, 134, 154, 160, 170, 176, 236, 254, 260, 266, 274, 334, 356, 370, 376, 386, 436, 446, 506, 532, 544, 560, 566, 574, 590, 596, 604, 610, 650, 656, 680, 730, 736, 754, 944, 950, 974, 980, 994, 1016, 1036, 1066, 1078, 1100, 1106
OFFSET
1,1
LINKS
FORMULA
(P_n+1 - P_n)/2 is even but not divisible by 4.
MATHEMATICA
a = Table[Prime[n], {n, 2, 200}]; b = {}; Do[d = (a[[n + 1]] - a[[n]])/2; If[ EvenQ[ a[[n]] + d] && Mod[d, 6] == 3, b = Append[b, a[[n]] + d]], {n, 1, 198}]; b
Select[Mean/@Select[Partition[Prime[Range[200]], 2, 1], Divisible[(#[[2]]- #[[1]])/ 2, 3]&], EvenQ] (* Harvey P. Dale, May 09 2021 *)
CROSSREFS
Cf. A024675, A072570. A072568 is union of A072570 and this sequence.
Sequence in context: A133635 A167705 A061673 * A307033 A058763 A291158
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