T(2n+6,n), array T as in A051168; a count of Lyndon words.

Terms

a(0) =0a(1) =1a(2) =4a(3) =18a(4) =70a(5) =273a(6) =1026a(7) =3876a(8) =14520a(9) =54477a(10) =204248a(11) =766935a(12) =2882934a(13) =10855425a(14) =40939888a(15) =154663938a(16) =585260496a(17) =2218309470a(18) =8421352956a(19) =32018897274a(20) =121918083980a(21) =464879984481