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A124518
Numbers k such that 10k-1 and 10k+1 are twin primes.
10
3, 6, 15, 18, 24, 27, 42, 57, 60, 66, 81, 102, 105, 123, 129, 132, 162, 195, 213, 231, 234, 255, 273, 279, 297, 300, 312, 330, 333, 336, 339, 354, 393, 402, 405, 423, 426, 465, 480, 501, 510, 528, 552, 564, 585, 588, 609, 627, 630, 636, 645, 657, 666, 669, 678
OFFSET
1,1
COMMENTS
All terms are divisible by 3. - Robert Israel, Apr 07 2019
LINKS
MAPLE
select(t -> isprime(10*t+1) and isprime(10*t-1), [seq(i, i=3..1000, 3)]); # Robert Israel, Apr 07 2019
MATHEMATICA
Select[Range[678], And @@ PrimeQ[{-1, 1} + 10# ] &] (* Ray Chandler, Nov 16 2006 *)
KEYWORD
nonn
AUTHOR
Artur Jasinski, Nov 04 2006
STATUS
approved