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A264914 Number of 9-ascent sequences of length n with no consecutive repeated letters. 2
1, 1, 9, 90, 945, 10440, 121065, 1470855, 18688680, 247924425, 3428559573, 49353455856, 738477897552, 11471175099726, 184755890053173, 3081830366508444, 53182355345412138, 948482464405185843, 17465164002387664056, 331740754587283644945, 6494261833979742949884 (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+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

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Last modified December 4 20:32 EST 2022. Contains 358570 sequences. (Running on oeis4.)