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%I #11 Jun 19 2018 03:28:11
%S 2,2,3,2,17,7,7,3,61,29,167,401,167,19,311,461,97,919,47,71,1483,107,
%T 13,1571,821,1361,769,239,163,4229,593,373,1571,173,6229,3331,1879,
%U 2837,2633,12329,2311,269,4159,1217,9719,509,3049,8429,307,6121,7919
%N a(n) is the smallest prime p such that p*n! +- 1 are twin primes.
%H Harry J. Smith, <a href="/A064998/b064998.txt">Table of n, a(n) for n = 2..200</a>
%e a(6) = 17 because 17*6! = 12240, 12240 + 1 and 12240 - 1 are twin primes, and there is no prime less than 17 for which this pairing will work.
%t Do[k = 1; While[ !PrimeQ[ Prime[k]*n! - 1] || !PrimeQ[ Prime[k]*n! + 1], k++ ]; Print[ Prime[k]], {n, 2, 75} ]
%o (PARI) { allocatemem(932245000); for (n=2, 200, f=n!; p=2; while (!isprime(p*f + 1) || !isprime(p*f - 1), p=nextprime(p + 1)); write("b064998.txt", n, " ", p) ) } \\ _Harry J. Smith_, Oct 03 2009
%Y Cf. A051888, A064983.
%K nonn
%O 2,1
%A _Robert G. Wilson v_, Oct 31 2001
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