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 A239910 #33 Aug 30 2022 14:25:12
%S A239910 0,0,1,6,45,435,5250,76608,1316574,26100000,587030895,14780620800,
%T A239910 412069511139,12604714327296,419801484375000,15123782440058880,
%U A239910 586049426860524300,24307340986526810112,1074495780444130114509,50429952000000000000000
%N A239910 Number of forests with three connected components in the complete graph K_{n}.
%C A239910 Equation (47) of Liu-Chow (1984) also gives the analogous formulas for four and five components. (They should also be entered into the OEIS, in case someone wants to help.)
%H A239910 Vincenzo Librandi, <a href="/A239910/b239910.txt">Table of n, a(n) for n = 1..200</a>
%H A239910 C. J. Liu and Yutze Chow, <a href="http://dx.doi.org/10.1137/0605038">On operator and formal sum methods for graph enumeration problems</a>, SIAM J. Algebraic Discrete Methods, 5 (1984), no. 3, 384-406. MR0752043 (86d:05059).
%F A239910 From _Harry Richman_, Aug 17 2022: (Start)
%F A239910 a(n) = n^(n-6)*(n-1)*(n-2)*(n^2+13*n+60)/8.
%F A239910 E.g.f.: T(x)^{3}/3!, where T(x) is the e.g.f. for the number of spanning trees in K_{n} A000272, i.e., T(x) = Sum_{i>=1} i^(i-2)*x^i/i!. (End)
%p A239910 f := n-> (n-1)*(n-2)*n^(n-6)*(n^2+13*n+60)/8; [seq(f(n),n=3..20)];
%t A239910 Table[(n-1)*(n-2) * n^(n - 6) * (n^2 + 13 n + 60)/8, {n, 1, 20}] (* _Vincenzo Librandi_, Apr 10 2014, simplified by _Vaclav Kotesovec_, Feb 20 2020 *)
%o A239910 (Magma) [(n-1)*(n-2)*n^(n-6)*(n^2+13*n+60)/8: n in [1..20]]; // _Vincenzo Librandi_, Apr 10 2014
%Y A239910 Cf. A000272, A083483.
%Y A239910 Column m=3 of A105599. A diagonal of A138464. - _Alois P. Heinz_, Apr 10 2014
%K A239910 nonn
%O A239910 1,4
%A A239910 _N. J. A. Sloane_, Apr 09 2014