A321840 Number of words w of length n such that each letter of the quaternary 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.

24, 60, 210, 609, 1961, 5952, 19255, 60812, 200281, 652011, 2185981, 7283988, 24809651, 84207955, 290756694, 1001820292, 3500030779, 12211804429, 43101225586, 151996648798, 541273095677, 1926487411495, 6914504463171, 24808989286716, 89666142346093

Offset

4,1

Links

Alois P. Heinz, Table of n, a(n) for n = 4..150

Crossrefs

Column k=4 of A257783.

Sequence in context: A250577 A242844 A185445 * A052759 A356911 A353229

Adjacent sequences: A321837 A321838 A321839 * A321841 A321842 A321843

Keyword

nonn

Author

Alois P. Heinz, Nov 19 2018

Status

approved