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 A007081 M3009 #20 Oct 08 2017 18:48:45
%S A007081 1,1,3,15,219,7839,777069,208836207,156458382975,328208016021561,
%T A007081 1946879656265710431,32834193098697741359313,
%U A007081 1582809785794578499063205301,218989607557709869788340418432175,87269441106898007902526099850864517077
%N A007081 Number of labeled Eulerian oriented graphs with n nodes.
%D A007081 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A007081 B. D. McKay, <a href="http://cs.anu.edu.au/~bdm/papers/LabelledEnumeration.pdf">Applications of a technique for labeled enumeration</a>, Congress. Numerantium, 40 (1983), 207-221.
%H A007081 B. D. McKay, <a href="http://users.cecs.anu.edu.au/~bdm/papers/rt.pdf">The asymptotic numbers of regular tournaments, Eulerian digraphs and Eulerian oriented graphs</a>, Combinatorica 10 (1990), 367-377.
%F A007081 a(n) = coefficient of [x_1*x_2*...*x_n]^(n-1) in Product_{1<=i<j<=n} (x_i^2 + x_j^2 + x_i*x_j). - _Sean A. Irvine_, Oct 08 2017
%K A007081 nonn,nice
%O A007081 1,3
%A A007081 _N. J. A. Sloane_, _Mira Bernstein_