%I A003019 M1179
%S A003019 1,1,2,4,9,20,48,114,282,703,1787,4583,11900,31131,82117,217954,581970,
%T A003019 1561704,4210263,11396488,30963024,84402984,230779071
%N A003019 Number of distinct values taken by 4^4^...^4 (with n 4's and parentheses 
               inserted in all possible ways).
%D A003019 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003019 R. K. Guy and J. L. Selfridge, The nesting and roosting habits of the 
               laddered parenthesis. Amer. Math. Monthly 80 (1973), 868-876.
%H A003019 <a href="Sindx_Par.html#parens">Index entries for sequences related to 
               parenthesizing</a>
%Y A003019 Cf. A002845, A003018, A145545, A145546, A145547, A145548, A145549, A145550, 
               A000081.
%Y A003019 Sequence in context: A036624 A034823 A036625 this_sequence A036626 A036722 
               A034824
%Y A003019 Adjacent sequences: A003016 A003017 A003018 this_sequence A003020 A003021 
               A003022
%K A003019 nonn,nice,more
%O A003019 1,3
%A A003019 N. J. A. Sloane (njas(AT)research.att.com).
%E A003019 a(12) - a(23) from Jon Schoenfield (jonscho(AT)hiwaay.net), Oct 11 2008