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A113484 a(n) = smallest composite integer > n and coprime to n.

%I A113484 #19 Mar 28 2021 15:53:56
%S A113484 4,9,4,9,6,25,8,9,10,21,12,25,14,15,16,21,18,25,20,21,22,25,24,25,26,
%T A113484 27,28,33,30,49,32,33,34,35,36,49,38,39,40,49,42,55,44,45,46,49,48,49,
%U A113484 50,51,52,55,54,55,56,57,58,63,60,77,62,63,64,65,66,85,68,69,70,81,72,77
%N A113484 a(n) = smallest composite integer > n and coprime to n.
%H A113484 G. C. Greubel, <a href="/A113484/b113484.txt">Table of n, a(n) for n = 1..1000</a>
%F A113484 a(p) = p+1 for prime p > 2. - _Michel Marcus_, Mar 13 2017
%t A113484 f[n_] := Block[{k = n + 1}, While[PrimeQ@k || GCD[k, n] > 1, k++ ]; k]; Array[f, 72] (* _Robert G. Wilson v_ *)
%o A113484 (PARI) a(n) = my(k = n+1); while(isprime(k) || (gcd(n,k) != 1), k++); k; \\ _Michel Marcus_, Mar 13 2017
%o A113484 (Python)
%o A113484 from sympy import isprime, gcd
%o A113484 def A113484(n):
%o A113484     k = n+1
%o A113484     while gcd(k,n) != 1 or isprime(k):
%o A113484         k += 1
%o A113484     return k # _Chai Wah Wu_, Mar 28 2021
%Y A113484 Cf. A113496.
%K A113484 nonn
%O A113484 1,1
%A A113484 _Leroy Quet_, Jan 11 2006
%E A113484 More terms from _Robert G. Wilson v_, Jan 13 2006