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A231901 Least k > n such that k!/n! + 1 is a prime, or 0 if no such k exists. 3

%I

%S 1,2,4,4,6,6,11,9,11,10,20,12,15,15,16,16,18,18,23,21,22,22,40,25,27,

%T 31,28,28,37,30,42,38,34,36,42,36,110,39,43,40,42,42,56,46,50,46,55,

%U 65,51,51,53,52,55,55,73,58,58,58,60,60,63,63,177,68,70,66,82,72

%N Least k > n such that k!/n! + 1 is a prime, or 0 if no such k exists.

%H Vincenzo Librandi, <a href="/A231901/b231901.txt">Table of n, a(n) for n = 0..1000</a>

%t Table[k = n + 1; While[! PrimeQ[k!/n! + 1], k++]; k, {n, 100}] (* _T. D. Noe_, Nov 18 2013 *)

%o (PARI) a(n) = {m = n; while(! isprime(m!/n! +1), m++); m;} \\ _Michel Marcus_, Mar 07 2014

%Y Cf. A002981, A035093, A057217, A075757, A075758, A231549.

%K nonn

%O 0,2

%A _Alex Ratushnyak_, Nov 15 2013

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Last modified October 23 08:57 EDT 2019. Contains 328345 sequences. (Running on oeis4.)