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A236408 Number of planar st-graphs with n edges. 0
1, 1, 3, 9, 33, 131, 561, 2535, 11971, 58579, 295297, 1526427, 8061879, 43380351, 237266225, 1316536991, 7399318871, 42065753191, 241628448517, 1400957386207 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

Ioannis G. Tollis, Giuseppe Di Battista, Peter Eades and Roberto Tamassia, Graph drawing, Prentice Hall Inc., Upper Saddle River, NJ, 1999. Algorithms for the visualization of graphs. MR2064104 (2005i:68067). See Sect. 4.2.

LINKS

Table of n, a(n) for n=1..20.

James Cranch, Representing and Enumerating Two-Dimensional Pasting Diagrams, 2014.

FORMULA

Conjecture: (n+2)*(n+3)*a(n) = 2*n*(2*n+1)*a(n-1) + (n-2)*(19*n-9)*a(n-2) + 14*(n-3)*(n-2)*a(n-3). - Vaclav Kotesovec, Feb 14 2014

CROSSREFS

Sequence in context: A151043 A151044 A247195 * A217617 A320181 A238113

Adjacent sequences:  A236405 A236406 A236407 * A236409 A236410 A236411

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 03 2014

STATUS

approved

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Last modified April 19 06:59 EDT 2019. Contains 322237 sequences. (Running on oeis4.)