A005336 Number of labeled nonseparable (or 2-connected) bipartite graphs with 2n nodes. (Formerly M3178)

1, 3, 355, 297619, 1120452771, 15350524923547, 738416821509929731, 126430202628042630866787, 78847417416749666369637926851, 183373380693566591129149674727445419, 1623847327688450079238401833083018045926051, 55669578575421273854874611540671620662810228887603

Offset

1,2

Comments

Nonseparable graphs are also called blocks.

References

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Andrew Howroyd, Table of n, a(n) for n = 1..50

F. Harary and R. W. Robinson, Labeled bipartite blocks, Canad. J. Math., 31 (1979), 60-68.

Crossrefs

Bisection of A004100.

Cf. A005334, A005335 (each part with n nodes).

Sequence in context: A037302 A341229 A157591 * A062226 A266454 A288948

Adjacent sequences: A005333 A005334 A005335 * A005337 A005338 A005339

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Name clarified and more terms added by Andrew Howroyd, Jan 03 2021

Status

approved