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 A186246 #27 Sep 08 2022 08:45:55
%S A186246 -1,2,-24,720,-40320,3628800,-479001600,87178291200,-20922789888000,
%T A186246 6402373705728000,-2432902008176640000,1124000727777607680000,
%U A186246 -620448401733239439360000,403291461126605635584000000,-304888344611713860501504000000,265252859812191058636308480000000
%N A186246 (2n+1)-th derivative of arccot(x) at x=0.
%C A186246 Also the negated (2n+1)-th derivative of arctan(x) at x=0. - _Stanislav Sykora_, Jan 06 2017
%H A186246 G. C. Greubel, <a href="/A186246/b186246.txt">Table of n, a(n) for n = 0..224</a>
%F A186246 a(n) = (-1)^(n+1)*A010050(n). - _M. F. Hasler_, Apr 22 2015
%p A186246 a:= n-> (2*n+1)! * coeftayl(arccot(x), x=0, 2*n+1):
%p A186246 seq (a(n), n=0..20); # _Alois P. Heinz_, Aug 18 2012
%t A186246 f[x_] := ArcCot[x]; Table[Derivative[2*n+1][f][0],{n,0,17}]
%t A186246 Table[(-1)^(n + 1)*(2*n)!, {n, 0, 50}] (* _G. C. Greubel_, Aug 10 2018 *)
%o A186246 (PARI) {a(n) = if( n<0, 0, -(-1)^n * (2*n)!)}; /* _Michael Somos_, Jan 07 2017 */
%o A186246 (Magma) [(-1)^(n+1)*Factorial(2*n): n in [0..50]]; // _G. C. Greubel_, Aug 10 2018
%Y A186246 Cf. A010050.
%K A186246 sign
%O A186246 0,2
%A A186246 _Michel Lagneau_, Aug 18 2012