A264913 Number of 8-ascent sequences of length n with no consecutive repeated letters.

1, 1, 8, 72, 684, 6876, 72924, 814056, 9544164, 117284766, 1507813722, 20243939784, 283383218358, 4129738188546, 62563457162916, 983985264479016, 16046556350152008, 271012423865891076, 4735104984115971090, 85496795448023574282, 1593757450233067980306

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+8))
    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 + 8}]]; 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=8 of A264909.

Sequence in context: A147840 A115970 A078995 * A082414 A145303 A098411

Adjacent sequences: A264910 A264911 A264912 * A264914 A264915 A264916

Keyword

nonn

Author

Alois P. Heinz, Nov 28 2015

Status

approved