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 A325080 #13 Apr 12 2019 18:53:40 %S A325080 31,181,191,331,401,421,521,641,911,971,991,1021,1291,1301,1511,1621, %T A325080 1831,1871,2011,2161,2281,2311,2381,2861,3001,3041,3061,3221,3301, %U A325080 3331,3391,3821,3931,4051,4211,4261,4271,4621,4691,4801,4871,4931,4951,5021,5171 %N A325080 Prime numbers congruent to 1, 16, 26, 31 or 36 modulo 55 neither representable by x^2 + x*y + 14*y^2 nor by x^2 + x*y + 69*y^2. %C A325080 Brink showed that prime numbers congruent to 1, 16, 26, 31 or 36 modulo 55 are representable by both or neither of the quadratic forms x^2 + x*y + 14*y^2 and x^2 + x*y + 69*y^2. A325079 corresponds to those representable by both, and this sequence corresponds to those representable by neither. %H A325080 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 A325080 Rémy Sigrist, <a href="/A325080/a325080.gp.txt">PARI program for A325080</a> %H A325080 Wikipedia, <a href="https://en.wikipedia.org/wiki/Kaplansky%27s_theorem_on_quadratic_forms">Kaplansky's theorem on quadratic forms</a> %e A325080 Regarding 31: %e A325080 - 31 is a prime number, %e A325080 - 31 = 0*55 + 31, %e A325080 - 31 is neither representable by x^2 + x*y + 14*y^2 nor by x^2 + x*y + 69*y^2, %e A325080 - hence 31 belongs to this sequence. %o A325080 (PARI) See Links section. %Y A325080 See A325067 for similar results. %Y A325080 Cf. A325079. %K A325080 nonn %O A325080 1,1 %A A325080 _Rémy Sigrist_, Mar 28 2019