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A005535 Number of semi-regular digraphs on n nodes.
(Formerly M5081)
1
1, 19, 916, 91212, 12888450 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

REFERENCES

Choudum, S. A.; Parthasarathy, K. R. Semi-regular relations and digraphs. Nederl. Akad. Wetensch. Proc. Ser. A. {75}=Indag. Math. 34 (1972), 326-334.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=3..7.

CROSSREFS

Sequence in context: A183473 A217826 A209353 * A171226 A247279 A192569

Adjacent sequences:  A005532 A005533 A005534 * A005536 A005537 A005538

KEYWORD

nonn,nice,more

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(7) from Sean A. Irvine, Jul 07 2016

STATUS

approved

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Last modified May 20 03:10 EDT 2019. Contains 323412 sequences. (Running on oeis4.)