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A292721
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Number of multisets of nonempty words with a total of n letters over 6-ary alphabet such that within each 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, 1, 4, 14, 67, 343, 2151, 9860, 53739, 279360, 1595454, 8733436, 53035750, 280946972, 1626421033, 9103196607, 53266673126, 300953629850, 1817236258604, 10114067087883, 59666856128423, 342703064143223, 2024687556279346, 11644875879288821, 70172335165701018
(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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G.f.: Product_{j>=1} 1/(1-x^j)^A226876(j).
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MAPLE
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b:= proc(n, i, t) option remember; `if`(t=1, 1/n!,
add(b(n-j, j, t-1)/j!, j=i..n/t))
end:
a:= proc(n) option remember; `if`(n=0, 1, add(add(d*d!*
b(d, 0, 6), d=numtheory[divisors](j))*a(n-j), j=1..n)/n)
end:
seq(a(n), n=0..35);
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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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