OFFSET
1,1
COMMENTS
Also number of "dessins d'enfants" with n edges. - Mark van Hoeij, Jan 23 2011
LINKS
Antonio Breda d'Azevedo, Alexander Mednykh and Roman Nedela, Table of n, a(n) for n = 1..30
Antonio Breda d'Azevedo, Alexander Mednykh and Roman Nedela, Enumeration of maps regardless of genus: Geometric approach, Discrete Mathematics, Volume 310, 2010, Pages 1184-1203.
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.
R. J. Mathar, Feynman diagrams of the QED vacuum polarization, vixra:1901.0148 (2019), Section V. Different from a(7) on.
R. de Mello Koch, S. Ramgoolam, Strings from Feynman graph counting: without large N, arXiv:1110.4858 [hep-th], 2012, (D.10). Different from a(7) on.
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 21 2010
STATUS
approved