A392427 - OEIS

%I #9 Jan 14 2026 10:38:18

%S 1,6,27,85,210,437,836,1442,2347,3634,5351,7700,10685,14500,19183,

%T 24914,31899,40220,50263,62099,75754,91655,109810,131001,154733,

%U 181506,211901,245359,282708,324803,371712,423507,479872,542141,609946,683574,764275,852370

%N Number of edges in a complete bipartite graph where the vertices in the two parts are placed on opposite sides of a parabola at integer x coordinates |x| = 1, 2, ...n.

%C See A392425 and A392426 for illustrations of the graphs.

%F a(n) = A392425(n) + A392426(n) - 1 by Euler's formula.

%Y Cf. A392425 (vertices), A392426 (regions), A392444 (integer y), A290132.

%K nonn

%O 1,2

%A _Scott R. Shannon_, Jan 11 2026