Number of Lyndon words on {1,2,3} with an even number of 1's and an even number of 2's.

Terms

a(0) =1a(1) =0a(2) =2a(3) =3a(4) =12a(5) =26a(6) =78a(7) =195a(8) =546a(9) =1452a(10) =4026a(11) =11010a(12) =30660a(13) =85254a(14) =239144a(15) =672195a(16) =1899120a(17) =5379738a(18) =15292914a(19) =43581852a(20) =124527988a(21) =356594898a(22) =1023295422a(23) =2941952130a(24) =8472886092a(25) =24440956260a(26) =70607383938