A086314 Total number of edges in the distinct simple graphs on n nodes.

0, 1, 6, 33, 170, 1170, 10962, 172844, 4944024, 270116280, 28022441260, 5448008695536, 1969579223350128, 1321964082404214704, 1649890513414726210320, 3840060942271653473695680, 16723638762440239422492944768, 136749695973639295091912681599872

Offset: 1

Author

Eric W. Weisstein, Jul 15 2003

Keywords

• nonn

Comments

a(n) = A000088(n)*n(n-1)/4.

a(n) = A000088(n)*A064038(n)/A014695(n).

Links

• Eric Weisstein's World of Mathematics, Simple Graph
• Eric Weisstein's World of Mathematics, Graph Edge

Crossrefs

Cf. A000088, A014695, A064038.

Programs

Mathematica

<< Combinatorica`; Table[D[GraphPolynomial[n, x], x] /. x -> 1, {n, 18}]  (* Geoffrey Critzer, Sep 29 2012 *)
<< Combinatorica`; Table[Binomial[n, 2] NumberOfGraphs[n]/2, {n, 18}] (* Eric W. Weisstein, May 17 2017 *)