A008323 Number of simple connected regular bipartite graphs with 2n nodes.

1, 1, 1, 2, 3, 5, 12, 34, 218, 4278, 431165, 162267174, 201636689352, 777816803938932, 9865957936943859185, 395886667549681686369527, 53716176608076643470380213991, 23524515269630339982914608683548933, 35682168849414944013547274439525153167248

Offset

0,4

Links

Table of n, a(n) for n=0..18.

Brendan McKay and E. Rogoyski, Latin squares of order ten, Electron. J. Combinatorics, 2 (1995) #N3.

Crossrefs

For n > 1, these are the row sums of triangle A008326.

Cf. A005142, A008324.

Sequence in context: A228905 A369847 A306038 * A000997 A266541 A301929

Adjacent sequences: A008320 A008321 A008322 * A008324 A008325 A008326

Keyword

nonn,hard,nice

Author

Brendan McKay

Extensions

a(10) corrected and a(11) added by Brendan McKay, Sep 06 2018

a(0)=1 prepended and terms a(12) and beyond from Andrew Howroyd, Apr 03 2020

Status

approved