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

%I A124569 #15 May 19 2023 01:36:21
%S A124569 1,11,13,15,17,29,31,33,35,37,51,53,55,65,67,83,85,87,89,91,101,103,
%T A124569 105,107,109,127,137,139,155,157,159,161,177,179,181,191,193,195,197,
%U A124569 199,209,211,213,215,217,227,229,231,233,235,247,249,251,253,263,265,267
%N A124569 Numbers k such that k, k+2, k+4 and k+6 are squarefree.
%C A124569 Numbers k, k+2, k+4 and k+6 are four successive odd squarefree numbers.
%H A124569 Robert Israel, <a href="/A124569/b124569.txt">Table of n, a(n) for n = 1..10000</a>
%p A124569 filter:= proc(n) andmap(numtheory:-issqrfree,[n,n+2,n+4,n+6]) end proc:
%p A124569 select(filter, [seq(i,i=1..1000,2)]); # _Robert Israel_, Jun 08 2021
%t A124569 okQ[n_] := AllTrue[n + {0, 2, 4, 6}, SquareFreeQ];
%t A124569 Select[Range[1, 1000, 2], okQ] (* _Jean-François Alcover_, May 18 2023 *)
%o A124569 (PARI) isok(n) = issquarefree(n) && issquarefree(n+2) && issquarefree(n+4) && issquarefree(n+6); \\ _Michel Marcus_, Oct 11 2013
%Y A124569 Cf. A007675, A024556.
%K A124569 nonn
%O A124569 1,2
%A A124569 _Zak Seidov_, Dec 27 2006