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, 3].
A211305
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, 3].
Terms
- a(0) =1a(1) =4a(2) =14a(3) =49a(4) =173a(5) =617a(6) =2222a(7) =8076a(8) =29605a(9) =109384a(10) =407059a(11) =1524662a(12) =5743964a(13) =21751969a(14) =82752733a(15) =316107245a(16) =1211853152a(17) =4660656826a(18) =17974865576a(19) =69496877137a(20) =269292154210
External references
- oeis: A211305