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A321041
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Number of words of length 6n such that all letters of the n-ary alphabet occur at least once and are introduced in ascending order and which can be built by repeatedly inserting triples of identical letters into the initially empty word.
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2
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1, 1, 97, 29886, 16482191, 13337746758, 14329297278912, 19256258184412314, 31120996552066805175, 58830559749207291469515, 127426007577261157375345878, 311250333529456439224989700168, 846594239519776323268829614117536, 2538054216720547203941994076323844425
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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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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