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A293885
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Number of sets of nonempty words with a total of n letters over quaternary alphabet containing the fourth letter such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
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2
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1, 5, 25, 102, 410, 1545, 5784, 21015, 76248, 272377, 974208, 3455177, 12287351, 43502174, 154554897, 547955950, 1950335934, 6937352521, 24777223885, 88515560121, 317513893877, 1139848959317, 4108296484542, 14823490668322, 53689879422115, 194704264528116
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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4,2
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LINKS
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FORMULA
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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