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 A220861 #27 Jan 25 2014 16:39:17 %S A220861 -4,-3,-20,-7,-11,-52,-68,-19,-23,-116,-31,-148,-164,-43,-47,-212,-59, %T A220861 -244,-67,-71,-292,-79,-83,-356,-388,-404,-103,-107,-436,-452,-127, %U A220861 -131,-548,-139,-596,-151,-628,-163,-167,-692,-179,-724,-191,-772,-788,-199 %N A220861 Choose smallest m>0 such that the n-th rational prime p ramifies in the imaginary quadratic extension field K = Q(sqrt(-m)); a(n) = discriminant(K). %C A220861 m=1 if p=2, otherwise m=p. %D A220861 David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989, Cor. 5.17, p. 105. %H A220861 Bruno Berselli, <a href="/A220861/b220861.txt">Table of n, a(n) for n = 1..1000</a> %F A220861 Let p = prime(n). Then a(n) = -4 if p = 2, -p if p == 3 mod 4, -4p if p == 1 mod 4. %Y A220861 Cf. A088192, A220862, A220863. %K A220861 sign %O A220861 1,1 %A A220861 _N. J. A. Sloane_, Dec 26 2012