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A264913 Number of 8-ascent sequences of length n with no consecutive repeated letters. 2
1, 1, 8, 72, 684, 6876, 72924, 814056, 9544164, 117284766, 1507813722, 20243939784, 283383218358, 4129738188546, 62563457162916, 983985264479016, 16046556350152008, 271012423865891076, 4735104984115971090, 85496795448023574282, 1593757450233067980306 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois 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

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Last modified September 20 10:32 EDT 2019. Contains 327229 sequences. (Running on oeis4.)