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 A354694 #6 Feb 16 2025 08:34:03 %S A354694 341,1729,1729,46657,46657,162401,399001,399001,399001,399001,488881, %T A354694 3057601,3057601,3828001,3828001,3828001,3828001,3828001,3828001, %U A354694 3828001,3828001,3828001,3828001,3828001,3828001,17098369,17098369,17098369,17098369,17236801,17236801 %N A354694 Least Euler pseudoprime to base 2 through base prime(n). %C A354694 a(n) is coprime to A002110(n). %H A354694 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/EulerPseudoprime.html">Euler Pseudoprime.</a> %o A354694 (PARI) a(n) = my(b, m, p=factorback(primes(n))); forcomposite(k=9, oo, if(gcd(k, p)==1, b=2; while((m=Mod(b, k)^(k\2)) == 1 || m == k-1, b++); if(b>prime(n), return(k)))); %Y A354694 Cf. A002110, A007324, A083876, A271221. %K A354694 nonn %O A354694 1,1 %A A354694 _Jinyuan Wang_, Jun 04 2022