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A053671 Least number coprime to n, n+1 and n+2.

%I A053671 #18 Jul 02 2025 16:01:59
%S A053671 5,5,7,7,11,5,5,7,7,7,5,5,11,11,7,5,5,7,11,13,5,5,7,7,7,5,5,11,7,7,5,
%T A053671 5,13,11,11,5,5,7,7,11,5,5,7,7,7,5,5,11,11,7,5,5,7,13,13,5,5,7,7,7,5,
%U A053671 5,11,7,7,5,5,11,11,11,5,5,7,7,13,5,5,7,7,7,5,5,11,11,7,5,5,7,11,11,5,5
%N A053671 Least number coprime to n, n+1 and n+2.
%H A053671 Reinhard Zumkeller, <a href="/A053671/b053671.txt">Table of n, a(n) for n = 1..10000</a>
%t A053671 a[n_] := (k = 5; While[! (CoprimeQ[k, n] && CoprimeQ[k, n+1] && CoprimeQ[k, n+2]), k++]; k); Table[a[n], {n, 1, 92}] (* _Jean-François Alcover_, Nov 30 2011 *)
%t A053671 lnc[n_]:=Module[{k=5,c=n+{0,1,2}},While[!And@@CoprimeQ[k,c],k=k+2];k]; Array[lnc,100] (* _Harvey P. Dale_, Mar 01 2015 *)
%o A053671 (Haskell)
%o A053671 a053671 n = f $ drop 2 a000040_list where
%o A053671    f (p:ps) | (n `mod` p) * ((n+1) `mod` p) * ((n+2) `mod` p) > 0 = p
%o A053671             | otherwise = f ps
%o A053671 -- _Reinhard Zumkeller_, Mar 19 2011
%Y A053671 Cf. A053669-A053674.
%K A053671 nonn,easy,nice
%O A053671 1,1
%A A053671 _Henry Bottomley_, Feb 15 2000
%E A053671 More terms from _James Sellers_, Feb 22 2000