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Number of labeled 4-chromatic (i.e., chromatic number = 4) graphs on n nodes.
2

%I #12 Dec 02 2018 03:00:32

%S 0,0,0,1,65,5042,605545,120653315,40885736829,23907349095479,

%T 24391928745798217

%N Number of labeled 4-chromatic (i.e., chromatic number = 4) graphs on n nodes.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/n-ChromaticGraph.html">n-Chromatic Graph</a>

%F a(n) = A084280(n) - A084279(n). - _Andrew Howroyd_, Dec 02 2018

%Y Cf. A084270, A084271, A084279, A084280.

%K nonn,more

%O 1,5

%A _Eric W. Weisstein_, May 24 2003

%E a(7)-a(11) from _Andrew Howroyd_, Dec 02 2018