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A321839
Number of words w of length n such that each letter of the ternary alphabet is used at least once and for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.
2
6, 12, 35, 87, 232, 599, 1591, 4202, 11262, 30221, 81834, 222321, 607871, 1668296, 4601369, 12737394, 35401272, 98716505, 276192166, 774988564, 2180739865, 6151939960, 17396648770, 49303165809, 140018238988, 398407130710, 1135670120668, 3242697225865
OFFSET
3,1
LINKS
Vaclav Kotesovec, Recurrence (of order 7)
FORMULA
a(n) ~ 797 * 3^(n - 3/2) / (32 * sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Nov 21 2018
CROSSREFS
Column k=3 of A257783.
Sequence in context: A268283 A372702 A196992 * A192029 A166636 A167338
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Nov 19 2018
STATUS
approved