Number of words of length 3n such that all letters of the ternary alphabet occur at least once and are introduced in ascending order and which can be built by repeatedly inserting triples into the initially empty word.
A321033
Number of words of length 3n such that all letters of the ternary alphabet occur at least once and are introduced in ascending order and which can be built by repeatedly inserting triples into the initially empty word.
Terms
- a(0) =12a(1) =198a(2) =2520a(3) =29886a(4) =347907a(5) =4048966a(6) =47431488a(7) =560528820a(8) =6684500548a(9) =80402461416a(10) =974694481735
External references
- oeis: A321033