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%I #8 Oct 05 2017 02:53:39
%S 1,1,2,4,9,20,48,115,286,719,1841,4762,12470,32918,87628,234795,
%T 633000,1715435,4671098,12772707,35059815,96567161,266818396,739344427
%N Number of distinct values taken by 7^7^...^7 (with n 7'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, A145548, A145549, A145550, A000081.
%K more,nonn
%O 1,3
%A _Jon E. Schoenfield_, Oct 13 2008
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