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Number of unlabeled connected loopless multigraphs with n nodes of degree less than n.
2

%I #39 May 06 2020 13:25:40

%S 0,1,1,2,12,146,5847,716141,300635753,430472002801,2117649544384420,

%T 36154420408979339192,2165755991529764630384554,

%U 459803603042851200545393118005

%N Number of unlabeled connected loopless multigraphs with n nodes of degree less than n.

%C Multigraphs are loopless.

%e From _Gheorghe Coserea_, Oct 11 2017: (Start)

%e For n=4 the a(4)=12 solutions are:

%e o--o--o--o o==o--o--o o--o==o--o o==o--o==o

%e o--o o==o o==o

%e | | | | | |

%e o--o o--o o==o

%e o--o o==o

%e | / | /

%e |/ |/

%e o--o o--o

%e o---o o--o o--o--o

%e |\ /| | /| |

%e | x | |/ | o

%e |/ \| o--o

%e o---o

%e (End)

%o (nauty/bash) for n in {1..8}; do geng -c -D$[${n}-1] ${n} -q | multig -m$[${n}-1] -D$[${n}-1] -u; done

%Y A diagonal of A334546.

%Y Cf. A001349, A289988.

%K nonn,more

%O 0,4

%A _Natan Arie Consigli_, Aug 19 2017

%E a(9)-a(13) from _Andrew Howroyd_, May 05 2020