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 A165936 A sequence of triples of squarefree consecutive integers each composed of exactly three primes. 0

%I

%S 1309,1310,1311,1885,1886,1887,2013,2014,2015,2665,2666,2667,3729,

%T 3730,3731,5133,5134,5135,6061,6062,6063,6213,6214,6215,6305,6306,

%U 6307,6477,6478,6479,6853,6854,6855,6985,6986,6987,7257,7258,7259,7953,7954,7955,8393

%N A sequence of triples of squarefree consecutive integers each composed of exactly three primes.

%F a(3n+1) = A066509(n+1); a(3n+2) = 1 + a(3n+1); a(3n+3) = 1 + a(3n+2). - _R. J. Mathar_, Nov 27 2011

%e 1309 = 7 * 11 * 17, 1310 = 2 * 5 * 131, 1311 = 3 * 19 * 23.

%t Select[Partition[Range[10000],3,1],AllTrue[#,SquareFreeQ]&&Union[ PrimeOmega[ #]] == {3}&]//Flatten (* _Harvey P. Dale_, Oct 02 2017 *)

%o (MAGMA) a:=[]; f:=func<n|forall{n+s: s in [0, 1, 2] |IsSquarefree(n+s) and #PrimeDivisors(n+s) eq 3}>; for k in [2..8500] do if f(k) then a:=a cat [k, k+1, k+2]; end if; end for; a; // _Marius A. Burtea_, Oct 05 2019

%K nonn

%O 1,1

%A Richard L. Peterson (rl_pete(AT)yahoo.com), Oct 01 2009

%E More terms from _Harvey P. Dale_, Oct 02 2017

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Last modified December 13 01:23 EST 2019. Contains 329963 sequences. (Running on oeis4.)