Words over signatures (derived from multisets and multinomials).

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =3a(5) =18a(6) =4a(7) =48a(8) =6a(9) =5a(10) =36a(11) =100a(12) =144a(13) =6a(14) =200a(15) =180a(16) =600a(17) =7a(18) =450a(19) =900a(20) =294a(21) =24a(22) =300a(23) =1800a(24) =8a(25) =882a(26) =7200a(27) =448a(28) =1200a(29) =1470