A124157 Maximal number of edges in a doubly linear graph with n nodes.

0, 1, 3, 6, 10, 15, 21, 28, 35

Offset

1,3

Comments

a(9) is known to be 34 or 35. I have put 35 here so as to distinguish this sequence from the triangular numbers. But the true value is (or was in 1997 at least) not known.

References

L. W. Beineke, Biplanar graphs: a survey, Computers Math. Applic., 34 (1997), 1-8.

Hutchinson, Joan P.; Shermer, Thomas; and Vince, Andrew; On representations of some thickness-two graphs. Comput. Geom. 13 (1999), 161-171.

Links

Table of n, a(n) for n=1..9.

Formula

For n >= 10, 6n-20 <= a(n) <= 6n-18.

Crossrefs

Sequence in context: A124158 A161208 A109444 * A033440 A067525 A130487

Adjacent sequences: A124154 A124155 A124156 * A124158 A124159 A124160

Keyword

nonn,more

Author

N. J. A. Sloane, Dec 02 2006

Status

approved