Number of sets of nonempty words with a total of n letters over ternary alphabet containing the third letter such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
A293884
Number of sets of nonempty words with a total of n letters over ternary alphabet containing the third letter such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
Terms
- a(0) =1a(1) =4a(2) =16a(3) =53a(4) =173a(5) =532a(6) =1615a(7) =4785a(8) =14066a(9) =40908a(10) =118438a(11) =341253a(12) =981200a(13) =2815762a(14) =8075265a(15) =23149097a(16) =66373778a(17) =190376443a(18) =546401592a(19) =1569387414a(20) =4511532695a(21) =12980998062a(22) =37385342522a(23) =107771434819a(24) =310967929569a(25) =898108427259
External references
- oeis: A293884