Number of reduced words of length n in the Weyl group D_27.

Terms

a(0) =1a(1) =27a(2) =377a(3) =3627a(4) =27026a(5) =166230a(6) =878409a(7) =4098483a(8) =17222607a(9) =66165501a(10) =235124461a(11) =780112671a(12) =2435132466a(13) =7196829486a(14) =20245295242a(15) =54455027238a(16) =140596223184a(17) =349621224120a(18) =839832229131