cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A327660 Least number k > n - 2 such that k*n^k + 1 is prime.

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%I A327660 #5 Sep 21 2019 14:41:50
%S A327660 1,1,2,3,1242,91,34,17,12382,9,10,247
%N A327660 Least number k > n - 2 such that k*n^k + 1 is prime.
%C A327660 Different version of A240234. Some authors, like Caldwell (link), require that k + 2 > n before they use the term generalized Cullen for a prime of form k*n^k + 1.
%H A327660 Chris K. Caldwell, <a href="https://primes.utm.edu/top20/page.php?id=42">The Top Twenty: Generalized Cullen</a>.
%e A327660 To find a(9), consider numbers k*9^k + 1 where k > 7. The first time it is prime, is for k = 12382, so a(9) = 12382.
%o A327660 (PARI) for(b=1,+oo,for(k=b-1,+oo,if(ispseudoprime(k*b^k+1),print1(k,", ");next(2))))
%Y A327660 Cf. A240234, A327661, A240235.
%K A327660 nonn,hard,more
%O A327660 1,3
%A A327660 _Jeppe Stig Nielsen_, Sep 21 2019