Number T(n,k) of words w of length n such that each letter of the k-ary 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; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

A257783

Number T(n,k) of words w of length n such that each letter of the k-ary 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; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =0a(4) =1a(5) =2a(6) =0a(7) =1a(8) =3a(9) =6a(10) =0a(11) =1a(12) =7a(13) =12a(14) =24a(15) =0a(16) =1a(17) =12a(18) =35a(19) =60a(20) =120a(21) =0a(22) =1a(23) =25a(24) =87a(25) =210a(26) =360a(27) =720a(28) =0a(29) =1

External references