Number of reduced words of length n in Coxeter group on 21 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.

A163145

Number of reduced words of length n in Coxeter group on 21 generators S_i with relations (S_i)^2 = (S_i S_j)^4 = I.

Terms

    a(0) =1a(1) =21a(2) =420a(3) =8400a(4) =167790a(5) =3351600a(6) =66948210a(7) =1337288400a(8) =26712295890a(9) =533577313500

External references