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 A103975 #25 Mar 23 2024 12:20:10
%S A103975 16,240,3360,46816,652080,9082320,126500416,1761923520,24540428880,
%T A103975 341804080816,4760716702560,66308229755040,923554499868016,
%U A103975 12863454768397200,179164812257692800,2495443916839302016,34757050023492535440,484103256412056194160
%N A103975 Smaller side in (a,a+1,a+1)-integer triangle with integer area.
%H A103975 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (15,-15,1).
%F A103975 a(n) = 15*a(n-1) - 15*a(n-2) + a(n-3) - _Max Alekseyev_, May 31 2007
%F A103975 a(n) = 2*A120892(2*n+1) - _Max Alekseyev_, May 31 2007
%F A103975 a(n) = (1/3)*((2 - sqrt(3))^(1 + 2*n) + (2 + sqrt(3))^(1 + 2*n) - 4). [_Terentyev Oleg_, Nov 12 2009]
%F A103975 a(n) = (4/3)*(A001570(n+1)-1).
%F A103975 G.f.: -16*x / ((x-1)*(x^2-14*x+1)). - _Colin Barker_, Apr 09 2013
%t A103975 a[n_] := 1/3 (-4 + (2 - Sqrt[3])^(1 + 2 n) + (2 + Sqrt[3])^(1 + 2 n)); A103975 = Expand[a /@ Range[1, 25]] (* _Terentyev Oleg_, Nov 12 2009 *)
%t A103975 LinearRecurrence[{15,-15,1},{16,240,3360},30] (* _Harvey P. Dale_, Apr 25 2012 *)
%Y A103975 Cf. A102341, A103974, A016064, A011945, A103772.
%Y A103975 Corresponding areas are given by A104008.
%K A103975 nonn,easy
%O A103975 1,1
%A A103975 _Zak Seidov_, Feb 23 2005
%E A103975 More terms from _Robert G. Wilson v_, Mar 24 2005
%E A103975 More terms from _Colin Barker_, Apr 09 2013