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A293968
Number of sets of exactly six nonempty words with a total of n letters over n-ary alphabet such that within each prefix of a word every letter of the alphabet is at least as frequent as the subsequent alphabet letter.
2
4, 62, 417, 2414, 12190, 57686, 260349, 1143710, 4936266, 21117128, 90035798, 384416432, 1649398948, 7133455202, 31173583589, 137947781614, 619247938106, 2824375268432, 13105785174035, 61940904739132, 298438345898409, 1466892183248186, 7358885205363735
OFFSET
14,1
LINKS
FORMULA
a(n) = [x^n y^6] Product_{j>=1} (1+y*x^j)^A000085(j).
MAPLE
g:= proc(n) option remember; `if`(n<2, 1, g(n-1)+(n-1)*g(n-2)) end:
b:= proc(n, i) option remember; series(`if`(n=0, 1, `if`(i<1, 0,
add(b(n-i*j, i-1)*binomial(g(i), j)*x^j, j=0..n/i))), x, 7)
end:
a:= n-> coeff(b(n$2), x, 6):
seq(a(n), n=14..40);
CROSSREFS
Column k=6 of A293815.
Cf. A000085.
Sequence in context: A376736 A232156 A316391 * A222791 A166028 A359620
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Oct 20 2017
STATUS
approved