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 A317887 #49 May 07 2025 11:17:41 %S A317887 1,2,4,18,56,60,88,1288,1784,3406,9250,11968,36216,57206,89148,107514, %T A317887 155410,202906 %N A317887 Numbers k such that 4^k - 3^k + 2^k is prime. %C A317887 1 is the only odd number in this sequence. %C A317887 a(15) > 65432. %C A317887 a(16) > 10^5. - _Michael S. Branicky_, Nov 21 2024 %e A317887 2 is in the sequence since 4^2 - 3^2 + 2^2 = 16 - 9 + 4 = 11 is prime. %t A317887 Select[Range[0, 5000], PrimeQ[4^# - 3^# + 2^#] &] %o A317887 (PARI) for(n=1, 5000, if(ispseudoprime(4^n-3^n+2^n), print1(n, ", "))) %Y A317887 Cf. A083324, A138699. %K A317887 nonn,more %O A317887 1,2 %A A317887 _Jinyuan Wang_, Aug 09 2018 %E A317887 a(13)-a(14) from _Giovanni Resta_, Aug 10 2018 %E A317887 a(15) from _Michael S. Branicky_, Nov 21 2024 %E A317887 a(16) from _Georg Grasegger_, Apr 07 2025 %E A317887 a(17)-a(18) from _Georg Grasegger_, May 06 2025