A324693 Number of simple graphs on n unlabeled nodes with minimum degree exactly 1.

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

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 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: A357711 A374656 A337291 * A276707 A350561 A083484

Adjacent sequences: A324690 A324691 A324692 * A324694 A324695 A324696

Keyword

nonn

Author

Andrew Howroyd, Sep 03 2019

Status

approved