A213291 Number of n-length words w over ternary alphabet such that 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, 3, 9, 18, 36, 74, 165, 367, 869, 2074, 5168, 13026, 33749, 88368, 235389, 632324, 1717202, 4693604, 12921864, 35751336, 99416633, 277527448, 777659128, 2185854247, 6162168724, 17416305904, 49342480077, 140094014788, 398558682310, 1135962971848

Offset: 0

Author

Alois P. Heinz, Jun 08 2012

Keywords

• nonn

Examples

			a(0) = 1: the empty word.
a(1) = 3: a, b, c for alphabet {a,b,c}.
a(2) = 9: aa, ab, ac, ba, bb, bc, ca, cb, cc.
a(3) = 18: aaa, aab, aac, aba, abc, aca, acb, baa, bac, bbb, bbc, bca, bcb, caa, cab, cba, cbb, ccc.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..200

Crossrefs

Column k=3 of A213276.