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.
%I A380903 #8 Feb 10 2025 09:33:11 %S A380903 2,2,1,2,3,4,10147,24 %N A380903 Least positive k such that n^n * k^k - 1 is a prime, or 0 if no such k exists. %C A380903 a(8) > 10^5 or a(8) = 0. %C A380903 a(9) = 0, a(10) = 3, a(11) = 3142, a(12) = 559, a(13) = 3558. %C A380903 a(14) > 10^5 or a(14) = 0. %F A380903 a(n) = A231735(n^n). %e A380903 The least k > 0 such that 4^4*k^k - 1 is a prime is k = 3, so a(4) = 3. %o A380903 (PARI) a(n) = for(k=1, oo, if(ispseudoprime(n^n*k^k-1), return(k))) \\ Does not terminate if a(n) = 0. %Y A380903 Cf. A228175, A231119, A231735. %K A380903 nonn,hard,more %O A380903 0,1 %A A380903 _Jason Yuen_, Feb 07 2025