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 A259191 #15 Mar 07 2020 12:39:17 %S A259191 3,0,0,4,1,0,0,0,2,0,0,1,1,0,0,3,1,0,0,0,0,0,0,1,8,0,0,1,0,0,0,0,1,0, %T A259191 0,6,0,0,0,1,1,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,1,2,0,0,6,0,0,0,0, %U A259191 1,0,0,0,0,0,0,1,0,0,0,1,2,0 %N A259191 Number of integral solutions to y^2 = x^3 + n*x^2 + n (with y nonnegative). %C A259191 If n is square there are at least two solutions, corresponding to x = 0 and x = -n. If n = 2^(2k) there are at least three solutions, corresponding to x = 0, x = -2^(2k), and x = 2^(6k-2) + 2^(2k). If n = 2k^2 + 2k, there is at least one solution, corresponding to x = 1. %o A259191 (Sage) %o A259191 for i in range(1,31): %o A259191 E=EllipticCurve([0,i,0,0,i]) %o A259191 print(len(E.integral_points())) %Y A259191 Cf. A081119, A081120. %K A259191 nonn %O A259191 1,1 %A A259191 _Morris Neene_, Jun 20 2015