Number of commutative elements in Coxeter group E_n.

Terms

a(0) =10a(1) =42a(2) =167a(3) =662a(4) =2670a(5) =10846a(6) =44199a(7) =180438a(8) =737762a(9) =3021000a(10) =12387990a(11) =50864885a(12) =209095841a(13) =860447494a(14) =3544046278a(15) =14608974346a(16) =60261567146a(17) =248726602105