The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.



(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A143660 Erroneous version of A170946. 0
2, 15, 20, 107 (list; graph; refs; listen; history; text; internal format)



The theory of dessins d'enfants was initiated by A. Grothendieck. "In this work, using the matrix model approach... we listed all the dessins d'enfants with no more than 4 edges. There are two 1-edge dessins, both of them are of genus zero, fifteen 2-edge dessins, among them only one is of genus 1, twenty 3-edge dessins: 14 sperical [sic] and 6 of genus 1 and one hundred seven 4-edge dessins: 57 spherical dessins, 46 dessins of genus 1 and 4 dessins of genus 2. The total number of dessins is 134."

Note: The fifteen for n=2 is a typo, it should be 5. The sum: 2+5+20+107=134 adds up if we replace fifteen by 5, and moreover, the section on 2-edge dessins lists all 5 (not fifteen) dessins. The correct version of this sequence is given by A170946. - Mark van Hoeij, Jan 23 2011


Table of n, a(n) for n=1..4.

N. M. Adrianov, N. Ya. Amburg, V. A. Dremov, Yu. A. Levitskaya, E. M. Kreines, Yu. Yu. Kochetkov, V. F. Nasretdinova and G. B. Shabat, Catalog of dessins d'enfants with <= 4 edges, arXiv:0710.2658 [math.AG], 2007.


Sequence in context: A091791 A281660 A244324 * A198391 A278889 A075722

Adjacent sequences:  A143657 A143658 A143659 * A143661 A143662 A143663





Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 15:55 EDT 2020. Contains 334684 sequences. (Running on oeis4.)