

A324693


Number of simple graphs on n unlabeled nodes with minimum degree exactly 1.


4



0, 1, 1, 4, 12, 60, 378, 3843, 64455, 1921532, 104098702, 10348794144, 1893781768084, 639954768875644, 400905675004630820, 467554784370658979194, 1019317687720204607541914, 4170177760438554428852944352, 32130458453030025927403299167172
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OFFSET

1,4


LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..50
Eric Weisstein's World of Mathematics, Minimum Vertex Degree
Gus Wiseman, The a(2) = 1 through a(5) = 12 unlabeled graphs with minimum degree 1.


FORMULA

a(n) = A002494(n)  A261919(n).
First differences of A141580.  Andrew Howroyd, Jan 11 2021


CROSSREFS

Column k = 1 of A294217.
A diagonal of A263293.
The labeled version is A327227.
The generalization to setsystems is A327335, with covering case A327230.
Unlabeled covering graphs are A002494.
Cf. A000088, A004110, A100743, A141580, A245797, A261919, A327105, A327362, A327364, A327366, A327372.
Sequence in context: A335656 A286073 A337291 * A276707 A083484 A088860
Adjacent sequences: A324690 A324691 A324692 * A324694 A324695 A324696


KEYWORD

nonn


AUTHOR

Andrew Howroyd, Sep 03 2019


STATUS

approved



