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Number of distinct values taken by 10^10^...^10 (with n 10's and parentheses inserted in all possible ways).
15

%I #7 Oct 05 2017 02:53:53

%S 1,1,2,4,9,20,48,115,286,719,1842,4766,12486,32972,87807,235365,

%T 634792,1720976,4688090,12824381,35216108,97037603,268229329,

%U 743562936,2066686470,5758171390,16079351152

%N Number of distinct values taken by 10^10^...^10 (with n 10's and parentheses inserted in all possible ways).

%H R. K. Guy and J. L. Selfridge, <a href="http://www.jstor.org/stable/2319392">The nesting and roosting habits of the laddered parenthesis</a>, Amer. Math. Monthly 80 (8) (1973), 868-876.

%H <a href="/index/Par#parens">Index entries for sequences related to parenthesizing</a>

%Y Cf. A002845, A003018, A003019, A145545, A145546, A145547, A145548, A145549, A000081.

%K more,nonn

%O 1,3

%A _Jon E. Schoenfield_, Oct 13 2008