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 A255730 #27 Oct 10 2024 01:11:09 %S A255730 1,2,4,16,52,80 %N A255730 Numbers k such that k^k - (k-1)^k + k is prime. %C A255730 a(6) corresponds to a prime having 153 digits. %C A255730 If it exists, a(7) > 5000. %C A255730 k does not have the form 20m+2 (which leads to a multiple of 5) or 42m+26 (which leads to a multiple of 7). %C A255730 If it exists, a(7) > 20000. - _Michael S. Branicky_, Oct 09 2024 %e A255730 4 is in the sequence because 4^4 - 3^4 + 4 = 179 is prime. %t A255730 Select[Range[1000], PrimeQ[#^# - (# - 1)^# + #] &] %o A255730 (Magma) [n: n in [0..500] |IsPrime(n^n - (n-1)^n + n)]; %o A255730 (PARI) is(n)=ispseudoprime(n^n-(n-1)^n+n) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A255730 Cf. A085682. %K A255730 nonn,more %O A255730 1,2 %A A255730 _Vincenzo Librandi_, Mar 13 2015