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%I #19 Jul 30 2014 08:16:28
%S 1,1,4,27,252,3020,44220,765030,15269520,345376080,8730489600,
%T 243911883600,7463164262400,248207881521600,8915064168410400,
%U 343923449355486000,14182674669779616000,622591172035376544000,28986699477880400256000,1426677017904959524704000
%N Number of words of length n over the alphabet {0,...,n-1} that avoid the pattern 1111.
%H Alois P. Heinz, <a href="/A239368/b239368.txt">Table of n, a(n) for n = 0..350</a>
%F Recursion: see Maple program.
%p a:= proc(n) option remember; `if`(n<3, n^n,
%p ((105*n^3-252*n^2+175*n-36) *a(n-1) -2*(n-1)^2 *a(n-2)
%p +2*(5*n-2)*(n-1)^2*(n-2)^2*a(n-3)) / (4*(2*n-1)*(5*n-7)))
%p end:
%p seq(a(n), n=0..20); # _Alois P. Heinz_, Jul 20 2014
%Y Cf. A012244, A239295.
%K nonn
%O 0,3
%A _Chad Brewbaker_, Mar 17 2014
%E a(8)-a(11) from _Alois P. Heinz_, Mar 17 2014
%E a(12)-a(19) from _Alois P. Heinz_, Jul 20 2014
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