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 A264913 Number of 8-ascent sequences of length n with no consecutive repeated letters. 2

%I

%S 1,1,8,72,684,6876,72924,814056,9544164,117284766,1507813722,

%T 20243939784,283383218358,4129738188546,62563457162916,

%U 983985264479016,16046556350152008,271012423865891076,4735104984115971090,85496795448023574282,1593757450233067980306

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

%H Alois P. Heinz, <a href="/A264913/b264913.txt">Table of n, a(n) for n = 0..200</a>

%H S. Kitaev, J. Remmel, <a href="https://arxiv.org/abs/1503.00914">p-Ascent Sequences</a>, arXiv:1503.00914 [math.CO], 2015.

%p b:= proc(n, i, t) option remember; `if`(n<1, 1, add(

%p `if`(j=i, 0, b(n-1, j, t+`if`(j>i, 1, 0))), j=0..t+8))

%p end:

%p a:= n-> (b(n-1, 0\$2)):

%p seq(a(n), n=0..30);

%t 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];

%t Table[a[n], {n, 0, 30}] (* _Jean-François Alcover_, Nov 09 2017, after _Alois P. Heinz_ *)

%Y Column k=8 of A264909.

%K nonn

%O 0,3

%A _Alois P. Heinz_, Nov 28 2015

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)