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A219894 Number of directed 2-regular graphs on n nodes without directed 2-cycles. 1
1, 4, 9, 55, 453, 4357, 47598, 569769, 7371560, 102525991, 1525164223 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,2

LINKS

Table of n, a(n) for n=5..15.

Gunnar Brinkmann, Generating regular directed graphs, Discrete Math., 313 (2012), 1-7.

CROSSREFS

Cf. A096368, A219889, A219890, A219891, A219892, A219893, A219895.

Sequence in context: A086692 A242036 A069507 * A203464 A152284 A109717

Adjacent sequences:  A219891 A219892 A219893 * A219895 A219896 A219897

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Nov 30 2012

EXTENSIONS

a(14) and a(15) from Brendan McKay, Mar 12 2019

STATUS

approved

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Last modified September 28 01:20 EDT 2020. Contains 337388 sequences. (Running on oeis4.)