This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A145550 #7 Oct 05 2017 02:53:53 %S A145550 1,1,2,4,9,20,48,115,286,719,1842,4766,12486,32972,87807,235365, %T A145550 634792,1720976,4688090,12824381,35216108,97037603,268229329, %U A145550 743562936,2066686470,5758171390,16079351152 %N A145550 Number of distinct values taken by 10^10^...^10 (with n 10's and parentheses inserted in all possible ways). %H A145550 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 A145550 <a href="/index/Par#parens">Index entries for sequences related to parenthesizing</a> %Y A145550 Cf. A002845, A003018, A003019, A145545, A145546, A145547, A145548, A145549, A000081. %K A145550 more,nonn %O A145550 1,3 %A A145550 _Jon E. Schoenfield_, Oct 13 2008