a(n) is the 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, 3].

A211278

a(n) is the 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, 3].

Terms

    a(0) =1a(1) =3a(2) =7a(3) =16a(4) =38a(5) =95a(6) =248a(7) =668a(8) =1838a(9) =5131a(10) =14470a(11) =41112a(12) =117475a(13) =337203a(14) =971515a(15) =2807744a(16) =8136090a(17) =23630215a(18) =68768210a(19) =200481036a(20) =585381973a(21) =1711647959a(22) =5011157073a(23) =14687848012a(24) =43095321203a(25) =126565380735a(26) =372030471493

External references