A034892 Number of balanced signed graphs on n unlabeled nodes.

1, 1, 3, 8, 39, 226, 2283, 36789, 1062679, 55717077, 5405078682, 972656526492, 325183692812200, 202373967993972497, 235081289816026793049, 511296223391186047847309, 2088912833728676472658628201, 16081914207958884651686215477871, 234010862353438997655954463710225233

Offset

0,3

References

R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.

Links

Andrew Howroyd, Table of n, a(n) for n = 0..50

Wikipedia, Signed graph

Formula

Euler transform of A318590.

Crossrefs

Cf. A004102, A005142, A318590.

Sequence in context: A288759 A180368 A108262 * A072687 A353718 A260817

Adjacent sequences: A034889 A034890 A034891 * A034893 A034894 A034895

Keyword

nonn,nice

Author

Ronald C. Read

Extensions

Name clarified and offset corrected by Andrew Howroyd, Sep 25 2018

a(0)=1 prepended and terms a(13) and beyond from Andrew Howroyd, Sep 25 2018

Status

approved