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A007170 Number of Q-graphs with 2n edges.
(Formerly M1877)
1
0, 1, 2, 8, 48, 328, 2335, 17133, 128262, 975547, 7518282, 58582564, 460769228, 3653385453, 29170737927, 234350263419, 1892956305974, 15364355580327, 125247311808502, 1024983176867450, 8417817643684208, 69355110426227296 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

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=1..22.

R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math. 31 (1986) no 1, 47-63.

FORMULA

a(n) = A007169(n) + (A294724(n) - A294728(n)) / 2. - Sean A. Irvine, Nov 07 2017

CROSSREFS

Cf. A007169, A294724, A294728.

Sequence in context: A152661 A177066 A228568 * A171455 A136722 A085615

Adjacent sequences:  A007167 A007168 A007169 * A007171 A007172 A007173

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(9) corrected and more terms from Sean A. Irvine, Nov 07 2017

STATUS

approved

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Last modified February 22 16:40 EST 2019. Contains 320399 sequences. (Running on oeis4.)