A086314 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,3

COMMENTS

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

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

LINKS

Table of n, a(n) for n=1..18.

Eric Weisstein's World of Mathematics, Simple Graph

Eric Weisstein's World of Mathematics, Graph Edge

MATHEMATICA

<< Combinatorica`; Table[D[GraphPolynomial[n, x], x] /. x -> 1, {n, 18}] (* Geoffrey Critzer, Sep 29 2012 *)