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.

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

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,look

Author

Alois P. Heinz, Aug 24 2012

Status

approved