Fast "exotic addition" a o b = [ a[1]+b[1], a[1]*b[2]+a[2]*b[1] ].

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =12a(5) =24a(6) =30a(7) =64a(8) =72a(9) =120a(10) =130a(11) =288a(12) =300a(13) =420a(14) =434a(15) =1024a(16) =1040a(17) =1296a(18) =1314a(19) =2400a(20) =2420a(21) =2860a(22) =2882a(23) =6912a(24) =6936a(25) =7800a(26) =7826a(27) =11760a(28) =11788a(29) =13020