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%I #10 Sep 10 2020 19:55:51
%S 1,3,9,25,71,201,571,1621,4611,13127,37415,106763,304991,872267,
%T 2497519,7159191,20545393,59028011,169782251,488892391,1409342969,
%U 4067217153,11750311255,33983345183,98387605609,285144063989,827236307471,2402300281607,6983098390213,20318073613437,59172567046657
%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, 1] as of [2, 2, 2].
%H Alois P. Heinz, <a href="/A211287/b211287.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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