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 A168629 Numbers n such that n,n+1 and sum of this two numbers have at least 3 distinct prime factors. 1
 1105, 1130, 1462, 1644, 1742, 1767, 2014, 2222, 2232, 2260, 2337, 2365, 2397, 2464, 2541, 2667, 2684, 2697, 2702, 2755, 2821, 2914, 3074, 3115, 3195, 3289, 3332, 3477, 3484, 3514, 3552, 3619, 3657, 3685, 3782, 3783, 3842, 3965, 4014, 4088, 4122, 4147, 4277 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..43. EXAMPLE 1105 = 5*13*17, 1106 = 2*7*79, 1105 + 1106 = 2211 = 3*11*67. MAPLE q:= n-> andmap(x-> nops(numtheory[factorset](x))>2, [n, n+1, 2*n+1]): select(q, [\$1..4600])[]; # Alois P. Heinz, Jun 29 2021 MATHEMATICA f[n_]:=Length[FactorInteger[n]]; lst={}; Do[If[f[n]>=3&&f[n+1]>=3&&f[n+n+1]>=3, AppendTo[lst, n]], {n, 8!}]; lst CROSSREFS Cf. A140077, A140078, A168626, A168628. Sequence in context: A107519 A331641 A343084 * A175521 A214607 A321870 Adjacent sequences: A168626 A168627 A168628 * A168630 A168631 A168632 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, Dec 01 2009 STATUS approved

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Last modified April 25 03:15 EDT 2024. Contains 371964 sequences. (Running on oeis4.)