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

Author

Alois P. Heinz, Aug 24 2012

Keywords

• nonn
• look

Comments

For the ordering of functions f_n see A215703.

Links

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

Crossrefs

Row n=2 of A215703.

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

Cf. A000081, A087803.

Programs

Maple

# load programs from A215703, then:
seq(A(2, n), n=1..100);