A139072 - OEIS

%I #14 Apr 01 2020 02:00:12

%S 1,2,3,4,7,3,11,7,8,5,13,4,28,10,7,8,43,6,21,5,7,16,48,4,14,17,9,7,

%T 241,5,61,11,17,17,8,10,44,38,16,6,131,9,63,12,6,43,73,9,15,10,19,14,

%U 64,11,12,9,24,32,641,5,89,31,8,8,14,11,71,19,25,7,151,6,78,62,15,35,15,22,87

%N Smallest parameter k such that (n+k!)/n is prime.

%C a(n) >= A002034(n). - _Charles R Greathouse IV_, Jul 15 2011

%C a(878) > 5000. - _Jinyuan Wang_, Apr 01 2020

%H Jinyuan Wang, <a href="/A139072/b139072.txt">Table of n, a(n) for n = 1..877</a>

%t a = {}; Do[k = 1; While[ ! PrimeQ[(k! + n)/n], k++ ]; AppendTo[a, k], {n, 1, 100}]; a

%o (PARI) pr(n)=denominator(n)==1 && ispseudoprime(n)

%o a(n)=my(k);until(pr(k++!/n+1),);k \\ _Charles R Greathouse IV_, Jul 15 2011

%Y Cf. A082672, A089085, A089130, A117141, A007749, A139056-A139066, A020458, A139068, A137390, A139070-A139075, A136019, A136020, A136026, A136027.

%K nonn

%O 1,2

%A _Artur Jasinski_, Apr 07 2008