Genus of modular group Gamma(n) = genus of modular curve Chi(n).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =3a(6) =5a(7) =10a(8) =13a(9) =26a(10) =25a(11) =50a(12) =49a(13) =73a(14) =81a(15) =133a(16) =109a(17) =196a(18) =169a(19) =241a(20) =241a(21) =375a(22) =289a(23) =476a(24) =421a(25) =568a(26) =529a(27) =806a(28) =577a(29) =1001