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A024607 Number of connected triangle-free graphs on n unlabeled nodes. 12
1, 1, 1, 3, 6, 19, 59, 267, 1380, 9832, 90842, 1144061, 19425052, 445781050, 13743625184, 566756900370, 31125101479652 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..17.

P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.

Eric Weisstein's World of Mathematics, Connected Graph

Eric Weisstein's World of Mathematics, Triangle-Free Graph

CROSSREFS

Inverse Euler transform of A006785.  Table of graphs on n nodes with clique number k is A126744.

Column k=1 of A283417.

Sequence in context: A320174 A248603 A052393 * A186022 A058818 A184937

Adjacent sequences:  A024604 A024605 A024606 * A024608 A024609 A024610

KEYWORD

hard,more,nonn,nice

AUTHOR

Peter J. Cameron

EXTENSIONS

2 more terms from Vladeta Jovovic, May 17 2008

2 more terms from A006785 by Martin Fuller, May 01 2015

STATUS

approved

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Last modified January 22 12:13 EST 2019. Contains 319363 sequences. (Running on oeis4.)