Posted by tpc at October 7th, 2009

for \Gamma_0(N)

Genus = 0
N= 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 16, 18 or 25
This corrects an error in Schoeneberg’s book. See Sloane’s sequence A091401.

Genus = 1
N= 11, 14, 15, 17, 19, 20, 21, 24, 27, 32, 36, 49 (presumably complete.)
See Sloane’s sequence A091403. Schoeneberg listed 24 as genus 3.

Genus = 2
N= 22, 23, 26, 28, 29, 31, 37, 50 (presumably complete.)
See Sloane’s sequence A091404.

A list for N=1 to 102 is also available here.