a(n) is the number of distinct billiard words with length n on an alphabet of 4 symbols.
A180239
a(n) is the number of distinct billiard words with length n on an alphabet of 4 symbols.
Terms
- a(0) =1a(1) =4a(2) =16a(3) =64a(4) =244a(5) =856a(6) =2776a(7) =8356a(8) =23032a(9) =59200a(10) =142624a(11) =324484a(12) =696256a(13) =1422436a(14) =2779900a(15) =5219452a(16) =9455596
External references
- oeis: A180239