a(n) = number of n-lettered words in the alphabet {1, 2, 3} with as many occurrences of the substring (consecutive subword) [1, 1] as of [2, 2].

A211277

a(n) = number of n-lettered words in the alphabet {1, 2, 3} with as many occurrences of the substring (consecutive subword) [1, 1] as of [2, 2].

Terms

    a(0) =1a(1) =3a(2) =7a(3) =17a(4) =43a(5) =109a(6) =285a(7) =753a(8) =2029a(9) =5529a(10) =15265a(11) =42531a(12) =119557a(13) =338357a(14) =963447a(15) =2756727a(16) =7921673a(17) =22843917a(18) =66078463a(19) =191637251a(20) =557045705a(21) =1622405135a(22) =4733543307a(23) =13831907295a(24) =40473954863a(25) =118578027369a(26) =347789276215

External references