

A361254


Number of nregular graphs on 2*n labeled nodes.


1



1, 1, 3, 70, 19355, 66462606, 2977635137862, 1803595358964773088, 15138592322753242235338875, 1793196665025885172290508971592750, 3040059281615704147007085764679679740691838, 74597015246986083384362428357508730776063716190667288, 26737694395324301026230134763403079891362936970900741153038680278
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OFFSET

0,3


COMMENTS

These graphs share the same degree sequence as the complete bipartite graphs K(n,n).


LINKS



FORMULA



PROG

(Common Lisp) ; See Links in A339847 for the graphcount function.
(graphcount (loop repeat (* 2 n) collect n)))
(PARI) \\ See Links in A295193 for GraphsByDegreeSeq.
a(n)={if(n==0, 1, vecsum(GraphsByDegreeSeq(2*n, n, (p, r)>valuation(p, x) >= nr)[, 2])) } \\ Andrew Howroyd, Mar 06 2023


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



