a(n) is the number of words of length n over the alphabet {0,1,2} with at least two 1's and exactly one occurrence of the subword 22.

A337142

a(n) is the number of words of length n over the alphabet {0,1,2} with at least two 1's and exactly one occurrence of the subword 22.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =3a(5) =18a(6) =69a(7) =216a(8) =597a(9) =1518a(10) =3633a(11) =8304a(12) =18306a(13) =39192a(14) =81906a(15) =167736a(16) =337623a(17) =669522a(18) =1310559a(19) =2536224a(20) =4858719a(21) =9224262a(22) =17370693a(23) =32472816a(24) =60302340a(25) =111305040a(26) =204307620a(27) =373111680a(28) =678188235a(29) =1227359874

External references