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 A033220 #30 Jul 08 2025 19:45:09
%S A033220 31,79,151,199,241,271,409,439,601,631,751,769,919,991,1009,1039,1129,
%T A033220 1201,1231,1249,1279,1321,1399,1471,1489,1609,1759,1801,1831,1879,
%U A033220 1951,1999,2089,2161,2239,2281
%N A033220 Primes of form x^2+30*y^2.
%D A033220 David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989.
%H A033220 Vincenzo Librandi and Ray Chandler, <a href="/A033220/b033220.txt">Table of n, a(n) for n = 1..10000</a> [First 1000 terms from Vincenzo Librandi]
%H A033220 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)
%F A033220 Equivalently, primes congruent to {1, 31, 49, or 79} (mod 120) - _T. D. Noe_, Apr 29 2008. [See e.g. Cox, p. 36. - _N. J. A. Sloane_, May 27 2014]
%F A033220 a(n) ~ 8n log n. - _Charles R Greathouse IV_, Nov 09 2012
%t A033220 QuadPrimes2[1, 0, 30, 10000] (* see A106856 *)
%o A033220 (Magma) [ p: p in PrimesUpTo(3000) | p mod 120 in {1, 31, 49, 79} ]; // _Vincenzo Librandi_, Jul 20 2012
%o A033220 (PARI) select(n->vecsearch([1,31,49,79],n%120), primes(400)) \\ _Charles R Greathouse IV_, Nov 09 2012
%Y A033220 Cf. A139643.
%K A033220 nonn,easy
%O A033220 1,1
%A A033220 _N. J. A. Sloane_