A176274 Numbers of the form 3k-1 with greatest prime divisor of the form 3m+1.

14, 26, 35, 38, 56, 62, 65, 74, 86, 95, 98, 104, 122, 134, 140, 143, 146, 152, 155, 158, 182, 185, 194, 206, 209, 215, 218, 224, 245, 248, 254, 260, 266, 278, 296, 302, 305, 314, 323, 326, 335, 338, 341, 344, 350, 362, 365, 380, 386, 392, 395, 398, 407, 416, 422, 434, 446

Offset: 1

Author

Vladimir Shevelev, Apr 14 2010

Keywords

• nonn

Comments

All numbers of the form 2p, where p==1(mod 3) is prime, are in the sequence.

Links

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

Crossrefs

Cf. A176262, A176258, A176257, A176256, A176255, A002148, A002145, A016813, A004767.

Programs

Mathematica

Select[Range[500],Divisible[#+1,3]&&Divisible[FactorInteger[#] [[-1,1]]-1, 3]&] (* Harvey P. Dale, Jul 29 2019 *)

PARI

isok(n) = ((n % 3) == 2) && ((vecmax(factor(n)[,1]) % 3) == 1); \\ Michel Marcus, Feb 08 2016

Extensions

More terms from Michel Marcus, Feb 08 2016