A264914 Number of 9-ascent sequences of length n with no consecutive repeated letters.

1, 1, 9, 90, 945, 10440, 121065, 1470855, 18688680, 247924425, 3428559573, 49353455856, 738477897552, 11471175099726, 184755890053173, 3081830366508444, 53182355345412138, 948482464405185843, 17465164002387664056, 331740754587283644945, 6494261833979742949884

Offset

0,3

Links

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

S. Kitaev, J. Remmel, p-Ascent Sequences, arXiv:1503.00914 [math.CO], 2015.

Maple

b:= proc(n, i, t) option remember; `if`(n<1, 1, add(
      `if`(j=i, 0, b(n-1, j, t+`if`(j>i, 1, 0))), j=0..t+9))
    end:
a:= n-> (b(n-1, 0$2)):
seq(a(n), n=0..30);

Mathematica

b[n_, i_, t_] := b[n, i, t] = If[n < 1, 1, Sum[If[j == i, 0, b[n - 1, j, t + If[j > i, 1, 0]]], {j, 0, t + 9}]]; a[n_] := b[n - 1, 0, 0];
Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Nov 09 2017, after Alois P. Heinz *)

Crossrefs

Column k=9 of A264909.

Sequence in context: A147841 A036258 A098399 * A143079 A233829 A165324

Adjacent sequences: A264911 A264912 A264913 * A264915 A264916 A264917

Keyword

nonn

Author

Alois P. Heinz, Nov 28 2015

Status

approved