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

Author

Alois P. Heinz, Nov 19 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 3..2102
• Vaclav Kotesovec, Recurrence (of order 7)

Crossrefs

Column k=3 of A257783.

Formula

a(n) ~ 797 * 3^(n - 3/2) / (32 * sqrt(Pi) * n^(3/2)). - Vaclav Kotesovec, Nov 21 2018