Number of subgroups of index 3 in fundamental group of a closed surface of characteristic -n.
A049293
Number of subgroups of index 3 in fundamental group of a closed surface of characteristic -n.
Terms
- a(0) =0a(1) =0a(2) =4a(3) =34a(4) =220a(5) =1330a(6) =7924a(7) =47194a(8) =281740a(9) =1685410a(10) =10095844a(11) =60522154a(12) =362968060a(13) =2177301490a(14) =13062263764a(15) =78368897914a(16) =470199235180
External references
- oeis: A049293