A057218 - OEIS

%I #10 Feb 21 2016 03:36:30

%S 2,3,7,5,11,7,43,17,19,11,23,13,79,29,31,17,103,19,457,41,43,23,47,

%T 577,151,53,163,29,59,31,156241,193,67,24481,71,37,223,229,79,41,83,

%U 43,1033,89,271,47,283,97,5881,101,103,53,107,109,331,113,6841,59,2355091201,61

%N a(n) = least prime of the form n*k! + 1.

%C First prime in the sequence n + 1, 2n + 1, 6n + 1, 24n + 1, 120n + 1, ...

%C If p is a prime then a(p-1) = p.

%e n=275, for k=1,..,24 {1+275*k!}={276,551,.......,170623310476640845824000001} and a(275)=170623310476640845824000001, the prime generated by A057217(275)=24 as 1+275*24!

%o (PARI) a(n) = k = 1; while (!isprime(p=1+n*k!), k++); p; \\ _Michel Marcus_, Feb 20 2016

%Y Primes arising in A057217.

%K nonn

%O 1,1

%A _Labos Elemer_, Sep 27 2000

%E More terms from Mark Hudson (mrmarkhudson(AT)hotmail.com), Aug 12 2004