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A320207
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Number of sets of nonempty words with a total of n letters over senary alphabet such that all letters occur at least once in the set.
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3
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4051, 111396, 1830822, 23420022, 257667120, 2564003346, 23761098837, 208907298660, 1764392910027, 14440938630576, 115269796672350, 901599089475150, 6935143271107130, 52608326918749428, 394424679767297550, 2927811687630339744, 21547773469006784856
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listen;
history;
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internal format)
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OFFSET
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6,1
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LINKS
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MAPLE
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h:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1, k)*binomial(k^i, j), j=0..n/i)))
end:
a:= n-> (k-> add((-1)^i*binomial(k, i)*h(n$2, k-i), i=0..k))(6):
seq(a(n), n=6..25);
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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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