A174101 Numbers k such that 2*k+1 and 6*k+1 are both primes of the form 6*m+1.

3, 6, 18, 21, 30, 33, 51, 63, 81, 90, 96, 105, 135, 138, 153, 156, 165, 168, 186, 216, 243, 261, 270, 300, 336, 363, 375, 378, 411, 426, 441, 453, 495, 510, 531, 543, 576, 585, 606, 615, 618, 648, 651, 723, 726, 741, 765, 798, 810, 828, 831, 846, 861, 891, 930

Offset

1,1

Comments

All terms are divisible by 3. - Robert Israel, Jun 27 2024

Links

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

Example

3 is a term: 3*2 + 1 = 7 and 3*6 + 1 = 19 are primes congruent to 1 (mod 6). - R. J. Mathar, Apr 16 2010

Maple

select(k -> isprime(2*k+1) and isprime(6*k+1), 3*[$1..1000]); # Robert Israel, Jun 27 2024

Mathematica

Select[Range[1000], With[{c={2, 6}#+1}, AllTrue[c, PrimeQ]&&AllTrue[(c-1)/6, IntegerQ]&]] (* Harvey P. Dale, Aug 08 2022 *)

Crossrefs

Cf. A002476, A065091.

Sequence in context: A078318 A193433 A074370 * A088339 A064400 A352786

Adjacent sequences: A174098 A174099 A174100 * A174102 A174103 A174104

Keyword

nonn

Author

Juri-Stepan Gerasimov, Mar 07 2010

Extensions

More terms from R. J. Mathar, Apr 16 2010

Status

approved