Number of 3n-length 4-ary words, either empty or beginning with the first letter of the alphabet, that can be built by repeatedly inserting triples of identical letters into the initially empty word.
A218474
Number of 3n-length 4-ary words, either empty or beginning with the first letter of the alphabet, that can be built by repeatedly inserting triples of identical letters into the initially empty word.
Terms
- a(0) =1a(1) =1a(2) =10a(3) =127a(4) =1810a(5) =27631a(6) =441604a(7) =7293700a(8) =123485914a(9) =2131511455a(10) =37368531010a(11) =663539143015
External references
- oeis: A218474