Word structures of length n using a 6-ary alphabet.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =15a(5) =52a(6) =203a(7) =876a(8) =4111a(9) =20648a(10) =109299a(11) =601492a(12) =3403127a(13) =19628064a(14) =114700315a(15) =676207628a(16) =4010090463a(17) =23874362200a(18) =142508723651a(19) =852124263684