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 A045688 #16 Feb 26 2018 00:55:48
%S A045688 0,0,0,1,29,1913,95,311148869,10193207,1664108363,2097555460001,
%T A045688 374694625074883,-48074332710505411,-4945837680716249285383,
%U A045688 -2229960300928783674917,-24840355960694307625698893,-4153678459092607393588136503,-61444568105054860319920405585007,-335560999071136641584079760493377
%N A045688 Numerators of expansion of tan(sin(x)) - sin(tan(x)).
%D A045688 V. I. Arnold, Huygens and Barrow, Newton and Hooke, Birkhäuser, Basel, 1990.
%e A045688 1/30*x^7 + 29/756*x^9 + 1913/75600*x^11 + O(x^12).
%t A045688 Plot[Tan[Sin[x]]-Sin[Tan[x]], {x, 0, π/2}] (* Shows plot, which, as _Bill Gosper_ and Neil Bickford remark, is ultraflat near 0 and has wild oscillations near Pi/2. - _N. J. A. Sloane_, Apr 11 2013 *)
%Y A045688 Cf. A045689 (denominators), A096664, A096671, A096712, A096716.
%K A045688 sign,frac
%O A045688 0,5
%A A045688 _N. J. A. Sloane_