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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. 2
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, 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, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For the ordering of functions f_n see A215703.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..7813

MAPLE

# load programs from A215703, then:

seq(A(2, n), n=1..100);

CROSSREFS

Row n=2 of A215703.

Number of distinct values of a(n) taken for functions with m x's: A028310.

Cf. A000081, A087803.

Sequence in context: A328985 A328196 A323307 * A272327 A212012 A322071

Adjacent sequences:  A215838 A215839 A215840 * A215842 A215843 A215844

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Aug 24 2012

STATUS

approved

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Last modified September 23 22:32 EDT 2020. Contains 337315 sequences. (Running on oeis4.)