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A007164 Number of P-graphs with 2n edges.
(Formerly M1784)
0
1, 2, 7, 31, 167, 999, 6495, 44619, 319463, 2356406, 17775821, 136405506, 1060866006, 8339982193, 66147792753, 528559162227, 4250413757583, 34368723106860, 279254390054538, 2278795583070154, 18667432144042678, 153452484745198722 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math., 31 (1986), 47-63.

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.

FORMULA

a(n) = (A003169(n) + 2 * A007165(n) + A007163(n)) / 4. - Sean A. Irvine, Nov 06 2017

CROSSREFS

Cf. A003169, A007163, A007165.

Sequence in context: A105216 A260532 A193657 * A321208 A005977 A199675

Adjacent sequences:  A007161 A007162 A007163 * A007165 A007166 A007167

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

EXTENSIONS

a(5), a(9), a(10) corrected and more terms from Sean A. Irvine, Nov 06 2017

STATUS

approved

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Last modified December 8 14:38 EST 2019. Contains 329865 sequences. (Running on oeis4.)