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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.
2

%I #4 Oct 18 2017 19:19:06

%S 1,4,16,53,173,532,1615,4785,14066,40908,118438,341253,981200,2815762,

%T 8075265,23149097,66373778,190376443,546401592,1569387414,4511532695,

%U 12980998062,37385342522,107771434819,310967929569,898108427259,2596180252466,7511411442182

%N 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.

%H Alois P. Heinz, <a href="/A293884/b293884.txt">Table of n, a(n) for n = 3..1000</a>

%F a(n) = A293742(n) - A293741(n).

%Y Column k=3 of A293113.

%Y Cf. A293741, A293742.

%K nonn

%O 3,2

%A _Alois P. Heinz_, Oct 18 2017