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

A211285

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

Terms

    a(0) =1a(1) =3a(2) =9a(3) =25a(4) =70a(5) =196a(6) =551a(7) =1552a(8) =4378a(9) =12375a(10) =35048a(11) =99449a(12) =282724a(13) =805270a(14) =2297862a(15) =6568973a(16) =18812535a(17) =53970516a(18) =155098263a(19) =446456103a(20) =1287215347a(21) =3717084781a(22) =10750037534a(23) =31135125908a(24) =90302734611a(25) =262263047834a(26) =762667932842

External references