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 A057102 #27 Aug 16 2024 21:03:48
%S A057102 24,96,120,240,336,384,480,720,840,960,1320,1344,1536,1920,1944,2016,
%T A057102 2184,2520,2880,3360,3696,3840,3960,4896,5280,5376,5544,6144,6240,
%U A057102 6840,6864,7680,7776,8064,8736,9240,9360,9720,10080,10296,10920,11520,12144
%N A057102 a(n) = 4 * A073120(n).
%C A057102 This sequence was originally described as the list of "congrua". But that name more properly refers to A256418.
%C A057102 Numbers of the form 4*(x^3*y-x*y^3) (where x,y are integers and x>=y). Squares of these numbers are of the form N^4-K^2 (where N belongs to A135786 and K to A135789 or A135790). Proof uses identity: (4(x^3y-xy^3))^2=(x^2+y^2)^4-(x^4 - 6x^2 y^2 + y^4)^2. - _Artur Jasinski_, Nov 29 2007, Nov 14 2008
%p A057102 N:= 10^5: # to get all terms <= N
%p A057102 select(`<=`,{seq(seq(4*(x^3*y-x*y^3),y=1..x-1),x=1..floor(sqrt(N/4+1)))},N);
%p A057102 # If using Maple 11 or earlier, uncomment the following line
%p A057102 # sort(convert(%, list)); # _Robert Israel_, Apr 06 2015
%t A057102 a = {}; Do[Do[w = 4x^3y - 4x y^3; If[w > 0 && w < 10000, AppendTo[a, w]], {x, y, 1000}], {y, 1, 1000}]; Union[a] (* _Artur Jasinski_, Nov 29 2007 *)
%Y A057102 Cf. A073120, A256418.
%K A057102 nonn,easy
%O A057102 1,1
%A A057102 _Henry Bottomley_, Aug 02 2000
%E A057102 Edited by _N. J. A. Sloane_, Apr 06 2015 at the suggestion of _Robert Israel_, Apr 03 2015