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A054922 Number of connected unlabeled symmetric relations (graphs with loops) having n nodes such that complement is also connected. 0
2, 0, 0, 10, 164, 2670, 56724, 1867860, 104538928, 10461483366, 1912179618740, 644464839239880, 402785011941549964, 468944407349226545614, 1021179521951204217530900, 4174755063830188009750183026 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..16.

V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.

FORMULA

a(n) = 2*A054921(n) - A000666(n).

CROSSREFS

Sequence in context: A213704 A278099 A000171 * A244139 A231031 A061848

Adjacent sequences:  A054919 A054920 A054921 * A054923 A054924 A054925

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, May 24 2000

EXTENSIONS

More terms from Vladeta Jovovic, Jul 17 2000

STATUS

approved

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Last modified December 8 06:50 EST 2016. Contains 278902 sequences.