A213864 Number of words w where each letter of the n-ary alphabet occurs 4 times 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.

1, 1, 19, 1075, 115955, 19558470, 4622269345, 1428739165560, 551211090935595, 256653852463806955, 140633739174235040170, 88931024447225475920050, 63897452586372538310261555, 51509615229665486538200354125, 46102293227619069563429377126200

Offset: 0

Author

Alois P. Heinz, Jun 23 2012

Keywords

• nonn

Examples

			a(0) = 1: the empty word.
a(1) = 1: aaaa.
a(2) = 19: aaaabbbb, aaababbb, aaabbabb, aaabbbab, aabaabbb, aabababb, aababbab, aabbaabb, aabbabab, abaaabbb, abaababb, abaabbab, ababaabb, abababab, baaaabbb, baaababb, baaabbab, baabaabb, baababab.
		

Crossrefs

Row n=4 of A213275.