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 A325074 #12 Apr 12 2019 08:25:34 %S A325074 109,149,269,389,409,449,569,829,929,1069,1129,1429,1489,1609,1889, %T A325074 1949,2129,2269,2309,2549,2609,2689,2749,2789,2909,2969,3109,3209, %U A325074 3229,3449,3709,3769,3889,4129,4349,4409,4889,4909,4969,5189,5309,5449,5569,5749,6029 %N A325074 Prime numbers congruent to 9 modulo 20 representable by x^2 + 100*y^2. %C A325074 Brink showed that prime numbers congruent to 9 modulo 20 are representable by exactly one of the quadratic forms x^2 + 20*y^2 or x^2 + 100*y^2. A325073 corresponds to those representable by the first form, and this sequence corresponds to those representable by the second form. %H A325074 David Brink, <a href="https://doi.org/10.1016/j.jnt.2008.04.007">Five peculiar theorems on simultaneous representation of primes by quadratic forms</a>, Journal of Number Theory 129(2) (2009), 464-468, doi:10.1016/j.jnt.2008.04.007, MR 2473893. %H A325074 Rémy Sigrist, <a href="/A325074/a325074.gp.txt">PARI program for A325074</a> %H A325074 Wikipedia, <a href="https://en.wikipedia.org/wiki/Kaplansky%27s_theorem_on_quadratic_forms">Kaplansky's theorem on quadratic forms</a> %e A325074 Regarding 4409: %e A325074 - 4409 is a prime number, %e A325074 - 4409 = 220*20 + 9, %e A325074 - 4409 = 53^2 + 100*4^2, %e A325074 - hence 4409 belongs to this sequence. %o A325074 (PARI) See Links section. %Y A325074 See A325067 for similar results. %Y A325074 Cf. A141883, A325073. %K A325074 nonn %O A325074 1,1 %A A325074 _Rémy Sigrist_, Mar 27 2019