%I A145549
%S A145549 1,1,2,4,9,20,48,115,286,719,1842,4766,12485,32969,87795,235326,634664,
%T A145549 1720573,4686829,12820504,35204254,97001655,268120807,743236814,
%U A145549 2065709551,5755253457
%N A145549 Number of distinct values taken by 9^9^...^9 (with n 9's and parentheses 
               inserted in all possible ways).
%D A145549 R. K. Guy and J. L. Selfridge, The nesting and roosting habits of the 
               laddered parenthesis. Amer. Math. Monthly 80 (1973), 868-876.
%H A145549 <a href="Sindx_Par.html#parens">Index entries for sequences related to 
               parenthesizing</a>
%Y A145549 Cf. A002845, A003018, A003019, A145545, A145546, A145547, A145548, A145550, 
               A000081.
%Y A145549 Sequence in context: A145547 A123467 A145548 this_sequence A145550 A000081 
               A124497
%Y A145549 Adjacent sequences: A145546 A145547 A145548 this_sequence A145550 A145551 
               A145552
%K A145549 more,nonn
%O A145549 1,3
%A A145549 Jon E. Schoenfield (jonscho(AT)hiwaay.net), Oct 13 2008