A283809 Squarefree numbers k such that 6k - 1 and 6k + 1 are twin primes.

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

Adjacent sequences: A283806 A283807 A283808 * A283810 A283811 A283812

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Mar 17 2017

Status

approved