Number of length 9 primitive (=aperiodic or period 9) n-ary words.

Terms

a(0) =0a(1) =0a(2) =504a(3) =19656a(4) =262080a(5) =1953000a(6) =10077480a(7) =40353264a(8) =134217216a(9) =387419760a(10) =999999000a(11) =2357946360a(12) =5159778624a(13) =10604497176a(14) =20661044040a(15) =38443356000a(16) =68719472640a(17) =118587871584a(18) =198359284536a(19) =322687690920a(20) =511999992000a(21) =794280037320