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%I #24 Nov 21 2013 13:11:33
%S 5,7,7,11,11,5,11,7,7,7,5,11,11,11,7,5,7,11,13,13,5,7,7,7,11,5,11,11,
%T 7,7,5,13,13,11,11,5,7,7,11,11,5,13,7,7,7,5,11,11,11,7,5,7,13,13,13,5,
%U 7,7,7,11,5,11,17,7,7,5,11,11,11,11,5,7,7,13,17,5,17,7,7,7,5,11,11,11,7
%N Least number coprime to n, n+1, n+2 and n+3.
%H Reinhard Zumkeller, <a href="/A053672/b053672.txt">Table of n, a(n) for n = 1..10000</a>
%F 5 <= a(n) <= (4 + o(1)) log n. - _Charles R Greathouse IV_, Jun 20 2013
%t a[n_] := (k = 5; While[ ! (CoprimeQ[k, n] && CoprimeQ[k, n+1] && CoprimeQ[k, n+2] && CoprimeQ[k, n+3]), k++]; k); Table[a[n], {n, 1, 85}](* _Jean-François Alcover_, Nov 30 2011 *)
%t Table[Module[{k=3},While[!And@@CoprimeQ[n+Range[0,3],Prime[k]],k++];Prime[k]],{n,90}] (* _Harvey P. Dale_, May 10 2012 *)
%o (Haskell)
%o import Data.List (elemIndex)
%o import Data.Maybe (fromJust)
%o a053672 n = 2 + fromJust
%o (elemIndex 1 $ map (gcd $ foldl1 lcm $ take 4 [n..]) [2..])
%o -- _Reinhard Zumkeller_, Sep 25 2011
%o (PARI) a(n)=forprime(p=5,,if((n+3)%p>3,return(p))) \\ _Charles R Greathouse IV_, Jun 20 2013
%Y Cf. A053669-A053674, A226891.
%K nonn,easy,nice
%O 1,1
%A _Henry Bottomley_, Feb 15 2000
%E More terms from _James A. Sellers_, Feb 22 2000
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