Paul Erdős (1913–1996) was a Hungarian mathematician. He considered mathematics to be a social activity and often collaborated on his papers, having 511 joint authors, many of whom also have their own collaborators. The Erdős number measures the "collaborative distance" between an author and Erdős. Thus, his direct co-authors have Erdős number one, theirs have number two, and so forth. Erdős himself has Erdős number zero.
There are more than 11,000 people with an Erdős number of two. This is a partial list of authors with an Erdős number of three or less. For more complete listings of Erdős numbers, see the databases maintained by the Erdős Number Project or the collaboration distance calculators maintained by the American Mathematical Society and by zbMATH.
Zero
Paul Erdős
One
A
János Aczél
Ron Aharoni
Martin Aigner
Miklós Ajtai
Leonidas Alaoglu
Yousef Alavi
Krishnaswami Alladi
Noga Alon
Nesmith Ankeny
Joseph Arkin
Boris Aronov
David Avis
B
László Babai
Frederick Bagemihl
Leon Bankoff
Paul T. Bateman
James Earl Baumgartner
Mehdi Behzad
Richard Bellman
Vitaly Bergelson
Arie Bialostocki
Andreas Blass
Ralph P. Boas Jr
Béla Bollobás
John Adrian Bondy
Joel Lee Brenner
John Brillhart
Thomas Craig Brown
W. G. Brown
Nicolaas Govert de Bruijn
R. Creighton Buck
Stefan Burr
Steve Butler
C
Neil J. Calkin
Peter Cameron
Paul A. Catlin
Gary Chartrand
Phyllis Chinn
Sarvadaman Chowla
Fan Chung
Kai Lai Chung
Václav Chvátal
Charles Colbourn
John Horton Conway
Arthur Herbert Copeland
Imre Csiszár
D
Harold Davenport
Dominique de Caen
Jean-Marie De Koninck
Jean-Marc Deshouillers
Michel Deza
Persi Diaconis
Gabriel Andrew Dirac
Jacques Dixmier
Yael Dowker
Underwood Dudley
Aryeh Dvoretzky
E
György Elekes
Peter D. T. A. Elliott
F
Vance Faber
Siemion Fajtlowicz
Ralph Faudree
László Fejes Tóth
William Feller
Peter C. Fishburn
Géza Fodor
Aviezri Fraenkel
Péter Frankl
Gregory Freiman
Wolfgang Heinrich Johannes Fuchs
Zoltán Füredi
G
Steven Gaal
Janos Galambos
Tibor Gallai
Fred Galvin
Joseph E. Gillis
Leonard Gillman
Abraham Ginzburg
Chris Godsil
Michael Golomb
Adolph Winkler Goodman
Basil Gordon
Ronald J. Gould
Ronald Graham
Sidney Graham
Andrew Granville
Peter M. Gruber
Branko Grünbaum
Hansraj Gupta
Richard K. Guy
Michael Guy
András Gyárfás
H
András Hajnal
Gábor Halász
Haim Hanani
Frank Harary
Zdeněk Hedrlín
Hans Heilbronn
Pavol Hell
Fritz Herzog
Alan J. Hoffman
Verner Emil Hoggatt Jr.