

A165542


Number of permutations of length n which avoid the patterns 4231 and 4123.


4



1, 1, 2, 6, 22, 89, 380, 1677, 7566, 34676, 160808, 752608, 3548325, 16830544, 80234659, 384132724, 1845829988, 8897740300, 43010084460, 208409687323, 1012046126532, 4923952560917, 23997719075657, 117136530812812, 572552052378494, 2802078324448067
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OFFSET

0,3


COMMENTS

G.f. conjectured to be nonDfinite (see Albert et al link).  Jay Pantone, Oct 01 2015


LINKS



EXAMPLE

There are 22 permutations of length 4 which avoid these two patterns, so a(4)=22.


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



