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 A139692 #27 Jun 29 2025 10:09:22
%S A139692 0,5,12,20,21,32,40,45,48,49,60,77,81,85,96,104,112,117,125,140,144,
%T A139692 148,165,169,189,192,216,221,224,229,252,256,257,260,272,285,288,320,
%U A139692 321,333,357,361,392,400,404,432,437,468,469,473,480,488,500,512,525,528,533,544,549
%N A139692 Nonnegative discriminants of the monic general quartic polynomials with integer coefficients.
%C A139692 Available discriminants of the general normalized quartic polynomial x^4+c*x^3+d*x^2+e*x+f with c,d,e,f >= 0.
%t A139692 aa = {}; b = 1; Do[Print[f]; Do[Do[Do[k = c^2 d^2 e^2 - 4 b d^3 e^2 - 4 c^3 e^3 + 18 b c d e^3 - 27 b^2 e^4 - 4 c^2 d^3 f + 16 b d^4 f + 18 c^3 d e f - 80 b c d^2 e f - 6 b c^2 e^2 f + 144 b^2 d e^2 f - 27 c^4 f^2 + 144 b c^2 d f^2 - 128 b^2 d^2 f^2 - 192 b^2 c e f^2 + 256 b^3 f^3; If[k >= 0 && k < 1000, AppendTo[aa, k]], {c, 0, 30}], {d, 0, 30}], {e, 0, 30}], {f, 0, 30}]; Union[aa]
%Y A139692 Cf. A014601, A042948, A139691.
%K A139692 nonn
%O A139692 1,2
%A A139692 _Artur Jasinski_, Apr 29 2008
%E A139692 Edited, and some missing terms inserted, by _Robert Israel_, May 16 2018