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 A033221 #32 Jul 08 2025 19:45:16
%S A033221 31,47,67,131,149,173,227,283,293,349,379,431,521,577,607,617,653,811,
%T A033221 839,853,857,919,937,971,1031,1063,1117,1187,1213,1237,1259,1303,1327,
%U A033221 1451,1493,1523,1559,1583,1619,1663,1721,1723,1741,1879,1931,1973,1993,2003,2017,2153,2273,2333,2341,2521,2531,2539,2543,2609,2707,2711,2713,2767,2797
%N A033221 Primes of form x^2+31*y^2.
%C A033221 Also primes of the form x^2+xy+8y^2. - _N. J. A. Sloane_, Jun 02 2014
%C A033221 Also primes of the form x^2-xy+8y^2 with x and y nonnegative. - _T. D. Noe_, May 07 2005
%C A033221 Primes p such that the polynomial X^3 + X + 1 splits mod p (see Williams and Hudson link). - _Robert Israel_, Jun 01 2020
%D A033221 David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989.
%H A033221 Vincenzo Librandi and Ray Chandler, <a href="/A033221/b033221.txt">Table of n, a(n) for n = 1..10000</a> [First 2000 terms from Vincenzo Librandi]
%H A033221 N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references)
%H A033221 K. Williams and R. Hudson, <a href="http://eudml.org/doc/206326">Representation of primes by the principal form of discriminant -D when the classnumber h(-D) is 3</a>, Acta Arithmetica 57.2 (1991): 131-153.
%p A033221 N:= 10000: # for terms <= N
%p A033221 S:= select(isprime,{31,seq(seq(x^2+31*y^2, y=1..floor(sqrt((N-x^2)/31))),
%p A033221 x=1..floor(sqrt(N)))}):
%p A033221 sort(convert(S,list)); # _Robert Israel_, Jun 01 2020
%t A033221 QuadPrimes2[1, 0, 31, 10000] (* see A106856 *)
%Y A033221 Primes in A243176.
%K A033221 nonn,easy
%O A033221 1,1
%A A033221 _N. J. A. Sloane_