A392426 Number of finite regions 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.

0, 2, 13, 44, 111, 233, 444, 767, 1247, 1925, 2834, 4064, 5637, 7641, 10110, 13132, 16803, 21182, 26439, 32627, 39789, 48111, 57628, 68664, 81072, 95078, 110933, 128456, 148009, 169949, 194346, 221283, 250683, 283099, 318435, 356838, 398831, 444607, 494070

Offset

1,2

Links

Table of n, a(n) for n=1..39.

Scott R. Shannon, Illustration for n = 2.

Scott R. Shannon, Illustration for n = 3.

Scott R. Shannon, Illustration for n = 4.

Scott R. Shannon, Illustration for n = 5.

Scott R. Shannon, Illustration for n = 6.

Scott R. Shannon, Illustration for n = 10.

Formula

a(n) = A392427(n) - A392425(n) + 1 by Euler's formula.

Crossrefs

Cf. A392425 (vertices), A392427 (edges), A392443 (integer y), A290131.

Sequence in context: A296807 A366310 A308731 * A025194 A392443 A084156

Adjacent sequences: A392423 A392424 A392425 * A392427 A392428 A392429

Keyword

nonn

Author

Scott R. Shannon, Jan 11 2026

Status

approved