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A131356 Numbers k such that p1 = 10k+9 and p2 = p1+2 are twin primes. 1
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
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
Sequence in context: A120626 A046058 A137271 * A191119 A089410 A118670
KEYWORD
nonn
AUTHOR
Zak Seidov, Sep 30 2007
STATUS
approved

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Last modified June 15 03:12 EDT 2024. Contains 373402 sequences. (Running on oeis4.)