Consider the Post tag system described in A284116 (but adapted to the alphabet {1,2}) ; sequence lists the words that terminate in the empty word.

A289675

Consider the Post tag system described in A284116 (but adapted to the alphabet {1,2}) ; sequence lists the words that terminate in the empty word.

Terms

    a(0) =1a(1) =2a(2) =11a(3) =12a(4) =111a(5) =112a(6) =121a(7) =122a(8) =1111a(9) =1121a(10) =1211a(11) =1221a(12) =2111a(13) =2121a(14) =2211a(15) =2221a(16) =11111a(17) =11112a(18) =11121a(19) =11122a(20) =11211a(21) =11212a(22) =11221a(23) =11222a(24) =12111a(25) =12112a(26) =12121a(27) =12122a(28) =12211a(29) =12212

External references