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A324693
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Number of simple graphs on n unlabeled nodes with minimum degree exactly 1.
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4
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0, 1, 1, 4, 12, 60, 378, 3843, 64455, 1921532, 104098702, 10348794144, 1893781768084, 639954768875644, 400905675004630820, 467554784370658979194, 1019317687720204607541914, 4170177760438554428852944352, 32130458453030025927403299167172
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OFFSET
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1,4
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LINKS
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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.
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FORMULA
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a(n) = A002494(n) - A261919(n).
First differences of A141580. - Andrew Howroyd, Jan 11 2021
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CROSSREFS
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Column k = 1 of A294217.
A diagonal of A263293.
The labeled version is A327227.
The generalization to set-systems 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
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KEYWORD
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nonn
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AUTHOR
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Andrew Howroyd, Sep 03 2019
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STATUS
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approved
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