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 A215971 #10 Oct 04 2014 10:45:39
%S A215971 1,1,2,4,9,20,48,115,286,717,1815,4574,11505,28546,69705,166010
%N A215971 Number of distinct values taken by 8th derivative of x^x^...^x (with n x's and parentheses inserted in all possible ways) at x=1.
%e A215971 a(4) = 4 because the A000108(3) = 5 possible parenthesizations of x^x^x^x lead to 4 different values of the 8th derivative at x=1: (x^(x^(x^x))) -> 269128; ((x^x)^(x^x)), ((x^(x^x))^x) -> 382520; (x^((x^x)^x)) -> 511216; (((x^x)^x)^x) -> 646272.
%p A215971 # load programs from A215703, then:
%p A215971 a:= n-> nops({map(f-> 8!*coeff(series(subs(x=x+1, f),
%p A215971 x, 9), x, 8), T(n))[]}):
%p A215971 seq(a(n), n=1..10);
%Y A215971 Cf. A000081 (distinct functions), A000108 (parenthesizations), A000012 (first derivatives), A028310 (2nd derivatives), A199085 (3rd derivatives), A199205 (4th derivatives), A199296 (5th derivatives), A199883 (6th derivatives), A002845, A003018, A003019, A145545, A145546, A145547, A145548, A145549, A145550, A082499, A196244, A198683, A215703, A215838. Column k=8 of A216368.
%K A215971 nonn,more
%O A215971 1,3
%A A215971 _Alois P. Heinz_, Aug 29 2012