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 A369863 #24 Feb 04 2024 15:50:25 %S A369863 13,29,43,47,53,59,61,67,73,79,83,97,113,127,131,137,149,151,157,163, %T A369863 167,181,197,211,227,229,233,241,251,281,311,313,317,331,349,379,383, %U A369863 389,397,401,409,419,433,449,463,467,479,487,499,503,547,557,563,569,571,577,587 %N A369863 Inert rational primes in the field Q(sqrt(-21)). %C A369863 Primes p such that Legendre(-21,p) = -1. %t A369863 Select[Range[3,600], PrimeQ[#] && JacobiSymbol[-21,#]==-1 &] (* _Stefano Spezia_, Feb 04 2024 *) %o A369863 (SageMath) [p for p in prime_range(3, 600) if legendre_symbol(-21, p) == -1] %Y A369863 Cf. inert rational primes in the imaginary quadratic field Q(sqrt(-d)) for the first squarefree positive integers d: A002145 (1), A003628 (2), A003627 (3), A003626 (5), A191059 (6), A003625 (7), A296925 (10), A191060 (11), A105885 (13), A191061 (14), A191062 (15), A296930 (17), A191063 (19), this sequence (21), A191064 (22), A191065 (23). %K A369863 nonn %O A369863 1,1 %A A369863 _Dimitris Cardaris_, Feb 03 2024