A finite sequence associated with the Lie algebra E_6.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =8a(7) =9a(8) =10a(9) =11a(10) =12a(11) =20a(12) =21a(13) =28a(14) =30a(15) =35a(16) =36a(17) =60a(18) =84a(19) =156