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Number of sets of nonempty words with a total of n letters over binary alphabet containing the second 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 #5 Oct 18 2017 19:25:37

%S 1,3,8,20,47,106,237,522,1146,2485,5406,11644,25157,53964,116003,

%T 247987,530999,1131889,2415431,5135838,10927816,23182209,49199697,

%U 104154808,220543306,465996956,984704338,2076988457,4380764354,9225209588,19424813915,40844509107

%N Number of sets of nonempty words with a total of n letters over binary alphabet containing the second 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="/A293883/b293883.txt">Table of n, a(n) for n = 2..1000</a>

%F a(n) = A293741(n) - A000009(n).

%Y Column k=2 of A293113.

%Y Cf. A000009, A293741.

%K nonn

%O 2,2

%A _Alois P. Heinz_, Oct 18 2017