a(n) = number of n-lettered words in the alphabet {1, 2, 3, 4} with as many occurrences of the substring (consecutive subword) [1, 2] as of [2, 3].
A211308
a(n) = number of n-lettered words in the alphabet {1, 2, 3, 4} with as many occurrences of the substring (consecutive subword) [1, 2] as of [2, 3].
Terms
- a(0) =1a(1) =4a(2) =14a(3) =50a(4) =182a(5) =668a(6) =2466a(7) =9156a(8) =34186a(9) =128308a(10) =483880a(11) =1832836a(12) =6970186a(13) =26603704a(14) =101875408a(15) =391282036a(16) =1506881410a(17) =5817328360a(18) =22507181024a(19) =87252861140a(20) =338857359792
External references
- oeis: A211308