OFFSET
1,4
COMMENTS
Original name: number of unlabeled complex components with n nodes.
We can find in "The Birth of the Giant Component", p. 2, see the first link:
"As each of the random graphs evolved, the story went, never once was there more than a single 'complex' component; i.e. there never were two or more components present simultaneously that were neither trees nor unicyclic."
So a complex component is a connected graph that is neither a tree nor an unicyclic graph.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..50
Svante Janson, Donald E. Knuth, Tomasz Luczak and Boris Pittel, The Birth of the Giant Component, [DOI], Rand. Struct. Alg. 4 (3) (1993) 233-358
N. J. A. Sloane, Illustration of initial terms of A001349.
EXAMPLE
a(4) = 2. See the two complex components with 4 nodes in the Sloane illustration.
CROSSREFS
KEYWORD
nonn
AUTHOR
Washington Bomfim, May 20 2008
EXTENSIONS
Name changed by Andrew Howroyd, Jan 16 2022
STATUS
approved