A046082 Number of ultraconnected graphs on n unlabeled nodes.

1, 1, 1, 2, 4, 19, 139, 2319, 77423, 4909331, 554491273

Offset

1,4

Comments

The ultraconnected graphs are related to the positive definite matrix completion problem.

Links

Table of n, a(n) for n=1..11.

W. W. Barrett, C. R. Johnson and R. Loewy, Critical graphs for the positive definite completion problem., SIAM J. Matrix Anal. Appl., Vol. 20 (1999), no. 1, 117-130.

Crossrefs

Sequence in context: A212923 A058130 A191563 * A048774 A061213 A063458

Adjacent sequences: A046079 A046080 A046081 * A046083 A046084 A046085

Keyword

hard,nonn

Author

Jason Grout (grout(AT)math.byu.edu), May 07 2003

Extensions

Broken link fixed by M. F. Hasler, Apr 05 2015

Status

approved