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%I #12 Oct 23 2017 14:45:57
%S 1,4,14,51,186,681,2507,9272,34450,128569,481865,1813294,6849679,
%T 25967722,98778134,376923683,1442500626,5535489345,21295353521,
%U 82114239566,317305643893,1228538872416,4765221729960,18513858369501,72039704814391,280707788515378,1095205252459856,4278094293847005
%N a(n) = number of n-lettered words in the alphabet {1, 2, 3, 4} with as many occurrences of the substring (consecutive subword) [1, 1] as of [1, 2].
%H Alois P. Heinz, <a href="/A211303/b211303.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 08 2012
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