A241841 Number of simple connected graphs on n nodes that are not trees.

0, 0, 1, 4, 18, 106, 842, 11094, 261033, 11716465, 1006700330, 164059829925, 50335907867918, 29003487462844902, 31397381142761234219, 63969560113225176156957, 245871831682084026519479939, 1787331725248899088890200452713, 24636021429399867655322650759363689

Offset: 1

Author

Travis Hoppe and Anna Petrone, Apr 29 2014

Keywords

• nonn

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..87 (terms 1..40 from Georg Fischer)
• Travis Hoppe and Anna Petrone, Encyclopedia of Finite Graphs
• T. Hoppe and A. Petrone, Integer sequence discovery from small graphs, arXiv preprint arXiv:1408.3644 [math.CO], 2014.
• T. Hoppe and A. Petrone, Integer sequence discovery from small graphs, Discr. Appl. Math. 201 (2016) 172-181.
• Eric Weisstein's World of Mathematics, Connected Graph
• Eric Weisstein's World of Mathematics, Cyclic Graph
• Eric Weisstein's World of Mathematics, Tree

Crossrefs

Cf. A000055, A001349, A286743, A306003.

Formula

a(n) = A001349(n) - A000055(n).