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A340413
Number of sets of nonempty words with a total of n letters over senary alphabet such that within each word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
2
1, 1, 3, 13, 60, 326, 2065, 9468, 51325, 268339, 1534485, 8421447, 51259855, 271291165, 1568129440, 8793678911, 51467662027, 290934776639, 1758652551885, 9783478684069, 57676281958781, 331610976485751, 1959129522047734, 11269354282135629, 67953764278371963
OFFSET
0,3
LINKS
FORMULA
G.f.: Product_{j>=1} (1+x^j)^A226876(j).
MAPLE
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:
g:= (n, k)-> `if`(k=0, `if`(n=0, 1, 0), n!*b(n, 0, k)):
h:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
add(h(n-i*j, i-1, k)*binomial(g(i, k), j), j=0..n/i)))
end:
a:= n-> h(n$2, min(n, 6)):
seq(a(n), n=0..32);
CROSSREFS
Column k=6 of A292795.
Cf. A226876.
Sequence in context: A367058 A353208 A340412 * A340414 A340415 A340416
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jan 06 2021
STATUS
approved