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A124569 Numbers k such that k, k+2, k+4 and k+6 are squarefree. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Numbers k, k+2, k+4 and k+6 are four successive odd squarefree numbers.
LINKS
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
Sequence in context: A152200 A277694 A179084 * A260826 A289699 A049722
KEYWORD
nonn
AUTHOR
Zak Seidov, Dec 27 2006
STATUS
approved

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Last modified May 25 07:10 EDT 2024. Contains 372782 sequences. (Running on oeis4.)