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.

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

Alois P. Heinz, Table of n, a(n) for n = 3..2102

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: A122608 A268283 A196992 * A192029 A166636 A167338

Adjacent sequences: A321836 A321837 A321838 * A321840 A321841 A321842

Keyword

nonn

Author

Alois P. Heinz, Nov 19 2018

Status

approved