A124569 Numbers k such that k, k+2, k+4 and k+6 are squarefree.

1, 11, 13, 15, 17, 29, 31, 33, 35, 37, 51, 53, 55, 65, 67, 83, 85, 87, 89, 91, 101, 103, 105, 107, 109, 127, 137, 139, 155, 157, 159, 161, 177, 179, 181, 191, 193, 195, 197, 199, 209, 211, 213, 215, 217, 227, 229, 231, 233, 235, 247, 249, 251, 253, 263, 265, 267

Offset

1,2

Comments

Numbers k, k+2, k+4 and k+6 are four successive odd squarefree numbers.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

filter:= proc(n) andmap(numtheory:-issqrfree, [n, n+2, n+4, n+6]) end proc:
select(filter, [seq(i, i=1..1000, 2)]); # Robert Israel, Jun 08 2021

Mathematica

okQ[n_] := AllTrue[n + {0, 2, 4, 6}, SquareFreeQ];
Select[Range[1, 1000, 2], okQ] (* Jean-François Alcover, May 18 2023 *)

Prog

(PARI) isok(n) = issquarefree(n) && issquarefree(n+2) && issquarefree(n+4) && issquarefree(n+6); \\ Michel Marcus, Oct 11 2013

Crossrefs

Cf. A007675, A024556.

Sequence in context: A277694 A179084 A375967 * A260826 A289699 A049722

Adjacent sequences: A124566 A124567 A124568 * A124570 A124571 A124572

Keyword

nonn

Author

Zak Seidov, Dec 27 2006

Status

approved