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A215841 Second derivative of f_n at x=1, where f_n is the n-th of all functions that are representable as x^x^...^x with m>=1 x's and parentheses inserted in all possible ways.

%I A215841 #12 Jul 18 2023 19:43:24
%S A215841 0,2,4,2,6,4,2,2,8,6,4,4,4,2,2,2,2,10,8,6,6,6,4,4,4,4,4,4,2,2,2,2,2,2,
%T A215841 2,2,2,12,10,8,6,8,8,6,6,4,4,4,6,6,6,6,4,4,4,4,4,4,4,4,4,4,4,4,4,2,2,
%U A215841 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,14
%N A215841 Second derivative of f_n at x=1, where f_n is the n-th of all functions that are representable as x^x^...^x with m>=1 x's and parentheses inserted in all possible ways.
%C A215841 For the ordering of functions f_n see A215703.
%H A215841 Alois P. Heinz, <a href="/A215841/b215841.txt">Table of n, a(n) for n = 1..7813</a>
%p A215841 # load programs from A215703, then:
%p A215841 seq(A(2, n), n=1..100);
%Y A215841 Row n=2 of A215703.
%Y A215841 Number of distinct values of a(n) taken for functions with m x's: A028310.
%Y A215841 Cf. A000081, A087803.
%K A215841 nonn,look
%O A215841 1,2
%A A215841 _Alois P. Heinz_, Aug 24 2012