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A320489 Number of connected nets on n unlabeled nodes. 4
1, 2, 6, 40, 581, 17954, 1376484, 275524246, 147627941386, 213261119287108, 836129127802137203, 8961301472286672235092, 264386586050074867407985650, 21609889100291959988235675761782, 4921292113269596022145447106163528469, 3138303995382684496665239674427115214538716 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..50

Edward A. Bender and E. Rodney Canfield, Enumeration of connected invariant graphs, Journal of Combinatorial Theory, Series B 34.3 (1983): 268-278. See p. 274.

N. J. A. Sloane, Transforms

FORMULA

EULERi transform of A004103.

CROSSREFS

Cf. A004103.

Sequence in context: A045846 A238818 A199574 * A135755 A337699 A051185

Adjacent sequences:  A320486 A320487 A320488 * A320490 A320491 A320492

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Oct 25 2018

EXTENSIONS

a(0)=1 prepended by Andrew Howroyd, Jan 26 2020

STATUS

approved

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Last modified September 29 10:54 EDT 2020. Contains 337428 sequences. (Running on oeis4.)