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A320213
Number of multisets of nonempty words with a total of n letters over ternary alphabet such that all letters occur at least once in the multiset.
3
13, 114, 672, 3334, 15030, 63978, 261880, 1043658, 4076856, 15688108, 59650623, 224625639, 839026657, 3112293273, 11474908920, 42080197859, 153566261268, 557943898644, 2018901838589, 7277784002970, 26142839723154, 93599166705077, 334072869753357
OFFSET
3,1
LINKS
MAPLE
b:= proc(n, k) option remember; `if`(n=0, 1, add(add(
d*k^d, d=numtheory[divisors](j))*b(n-j, k), j=1..n)/n)
end:
a:= n-> (k-> add(b(n, k-i)*(-1)^i*binomial(k, i), i=0..k))(3):
seq(a(n), n=3..30);
CROSSREFS
Column k=3 of A257740.
Cf. A320204.
Sequence in context: A230377 A254038 A221369 * A323037 A320617 A156969
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Oct 07 2018
STATUS
approved