Number of sets of nonempty words with a total of n letters over n-ary alphabet such that if a letter occurs in the set all predecessors occur at least once.
A319518
Number of sets of nonempty words with a total of n letters over n-ary alphabet such that if a letter occurs in the set all predecessors occur at least once.
Terms
- a(0) =1a(1) =1a(2) =4a(3) =27a(4) =218a(5) =2178a(6) =25529a(7) =343392a(8) =5205948a(9) =87740878a(10) =1626182463a(11) =32852520594a(12) =718169744206
External references
- oeis: A319518