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

0,2

Links

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

Example

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.

Crossrefs

Column k=3 of A213276.

Sequence in context: A127645 A000241 A028723 * A264365 A291143 A057578

Adjacent sequences: A213288 A213289 A213290 * A213292 A213293 A213294

Keyword

nonn

Author

Alois P. Heinz, Jun 08 2012

Status

approved