A084270 Number of labeled 2-chromatic (i.e., chromatic number = 2) graphs on n nodes.

0, 1, 6, 40, 375, 5176, 103236, 2922445, 116011230, 6433447396, 498234407451, 54007795331920, 8213123246906760, 1756336596363006841, 528975889250504033526, 224688018516023267969440, 134708289561117007261966815

Offset: 1

Author

Eric W. Weisstein, May 24 2003

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, n-Chromatic Graph

Crossrefs

Cf. A084271, A084272.

Formula

a(n) = A047864(n)-1. - Vladeta Jovovic, Jul 31 2003

Extensions

More terms from Vladeta Jovovic, Jul 31 2003

One further term from David Wasserman, Dec 13 2004