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%I #10 Sep 10 2020 20:03:39
%S 1,3,9,25,71,201,573,1635,4677,13399,38457,110559,318375,918281,
%T 2652687,7674389,22234411,64506957,187396863,545090409,1587454407,
%U 4628463753,13509904359,39475258065,115460419701,338030276619,990539965197,2905111047127,8527250269257,25049140759647,73637161597765
%N a(n) = number of n-lettered words in the alphabet {1, 2, 3} with as many occurrences of the substring (consecutive subword) [1, 1, 2] as of [1, 2, 2].
%H Alois P. Heinz, <a href="/A211290/b211290.txt">Table of n, a(n) for n = 0..1000</a>
%H Shalosh B. Ekhad and Doron Zeilberger, <a href="http://arxiv.org/abs/1112.6207">Automatic Solution of Richard Stanley's Amer. Math. Monthly Problem #11610 and ANY Problem of That Type</a>, arXiv preprint arXiv:1112.6207, 2011. See subpages for rigorous derivations of g.f., recurrence, asymptotics for this sequence.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Apr 07 2012
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