Euler characteristic of mapping class group Gamma_n.

Terms

a(0) =1a(1) =1a(2) =3a(3) =2a(4) =3a(5) =4a(6) =1a(7) =-6a(8) =45a(9) =-86a(10) =173a(11) =-100a(12) =2641a(13) =-48311a(14) =717766a(15) =-15527527a(16) =395694683a(17) =-11210796201a(18) =356923346235