a(n) = number of n-lettered words in the alphabet {1, 2, 3, 4} with as many occurrences of the substring (consecutive subword) [1, 1] as of [2, 2].
A211304
a(n) = number of n-lettered words in the alphabet {1, 2, 3, 4} with as many occurrences of the substring (consecutive subword) [1, 1] as of [2, 2].
Terms
- a(0) =1a(1) =4a(2) =14a(3) =50a(4) =180a(5) =650a(6) =2364a(7) =8640a(8) =31760a(9) =117350a(10) =435828a(11) =1626440a(12) =6097584a(13) =22958876a(14) =86796152a(15) =329371312a(16) =1254263360a(17) =4791746342a(18) =18360757572a(19) =70546266792a(20) =271734956048
External references
- oeis: A211304