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A283809
Squarefree numbers k such that 6k - 1 and 6k + 1 are twin primes.
1
1, 2, 3, 5, 7, 10, 17, 23, 30, 33, 38, 47, 58, 70, 77, 87, 95, 103, 107, 110, 137, 138, 143, 170, 177, 182, 205, 213, 215, 217, 238, 247, 278, 283, 287, 298, 313, 322, 347, 355, 357, 373, 385, 390, 397, 443, 455, 465, 467, 542, 543, 555, 562, 565, 577, 590, 593, 597, 642, 653, 655, 667, 670, 682
OFFSET
1,2
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[100], SquareFreeQ[#] && PrimeQ[6# - 1] && PrimeQ[6# + 1] &] (* Indranil Ghosh, Mar 17 2017 *)
PROG
{MAGMA) [n: n in [1..700] | IsSquarefree(n) and IsPrime(6*n-1) and IsPrime(6*n+1)];
(PARI) is(n)=isprime(6*n-1) && isprime(6*n+1) && issquarefree(n) \\ Charles R Greathouse IV, Mar 17 2017
CROSSREFS
Subsequence of A002822 and of A005117. Supersequence of A060212.
Sequence in context: A360464 A271063 A182521 * A104622 A033843 A075657
KEYWORD
nonn,easy
AUTHOR
STATUS
approved