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%I #11 Mar 09 2018 12:13:33
%S 1,1,1,18,18,8628,748668,2506980,228698250,228698250
%N a(n) is the smallest number m such that all the n numbers 1!*m+1, 2!*m+1, ..., n!*m+1 are prime.
%e a(5)=18 because each of the five numbers 1!*18+1, 2!*18+1, 3!*18+1, 4!*18+1 and 5!*18+1 is prime, and 18 is the smallest such number.
%e The corresponding primes are:
%e n=1: 2;
%e n=2: 2, 3;
%e n=3: 2, 3, 7;
%e n=4: 19, 37, 109, 433;
%e n=5: 19, 37, 109, 433, 2161;
%e n=6: 8629, 17257, 51769, 207073, 1035361, 6212161;
%e n=7: 748669, 1497337, 4492009, 17968033, 89840161, 539040961, 3773286721;
%e ...
%o (PARI) okm(m, n) = {for (k=1, n, if (! isprime(k!*m+1), return (0));); return (1);}
%o a(n) = {m = 1; while(! okm(m, n), m++); m;} \\ _Michel Marcus_, Jun 08 2014
%Y Cf. A177013.
%K more,nonn
%O 1,4
%A _Enoch Haga_ and _Farideh Firoozbakht_, May 20 2010
%E a(10) corrected by _Jon E. Schoenfield_, Mar 07 2018