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A131356 Numbers k such that p1=10k+9 and p2=p1+2 are twin primes (and p1^2 == p2^2 == 1 (mod 10)). 0

%I

%S 2,5,14,17,23,26,41,56,59,65,80,101,104,122,128,131,161,194,212,230,

%T 233,254,272,278,296,299,311,329,332,335,338,353,392,401,404,422,425,

%U 464,479,500,509,527,551,563,584,587,608,626,629,635,644,656,665,668,677

%N Numbers k such that p1=10k+9 and p2=p1+2 are twin primes (and p1^2 == p2^2 == 1 (mod 10)).

%C All numbers k == 2 (mod 3).

%C 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.

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

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

%K nonn

%O 1,1

%A _Zak Seidov_, Sep 30 2007

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Last modified February 1 17:02 EST 2023. Contains 359993 sequences. (Running on oeis4.)