A131356 - OEIS

A131356

Numbers k such that p1 = 10k+9 and p2 = p1+2 are twin primes.

2, 5, 14, 17, 23, 26, 41, 56, 59, 65, 80, 101, 104, 122, 128, 131, 161, 194, 212, 230, 233, 254, 272, 278, 296, 299, 311, 329, 332, 335, 338, 353, 392, 401, 404, 422, 425, 464, 479, 500, 509, 527, 551, 563, 584, 587, 608, 626, 629, 635, 644, 656, 665, 668, 677

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

All numbers k == 2 (mod 3).

All p1+1 are of form 30m with m=1, 2, 5, 6, 8, 9, 14, 19, 20, 22, 27, 34, 35, 41, 43, 44, 54, 65, 71, 77, 78, 85, 91, 93, 99, 100, 104, 110, 111, 112, 113, 118, 131, 134, 135, 141, 142, 155, 160, 167, 170, 176, 184, 188, 195, 196, 203, 209, 210, 212, 215, 219, 222, 223, 226, 229, 232, 245, 252, 253, 265, 267, 274, 281, 294, 299, 300, 308, 314, 321, 324, 331.

All p1 are of the form 6r-1 (=lesser of twin primes) with r=5m.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

filter:= k -> isprime(10*k+9) and isprime(10*k+11):

select(filter, [seq(i, i=2..1000, 3)]); # Robert Israel, Jan 11 2024

MATHEMATICA

Select[Range[1200], PrimeQ[10#+9]&&PrimeQ[10#+11]&]

CROSSREFS

Cf. A001359, A006512.

Sequence in context: A120626 A046058 A137271 * A191119 A089410 A118670

Adjacent sequences: A131353 A131354 A131355 * A131357 A131358 A131359

KEYWORD

nonn

AUTHOR

Zak Seidov, Sep 30 2007

STATUS

approved