A009820 Expansion of tanh(tanh(log(1+x))).

0, 1, -1, -2, 18, -44, -300, 3928, -12544, -193160, 3128040, -11235872, -311721168, 5932512496, -21553521808, -1023800851712, 21959034049920, -72153838392704, -5963595925511808, 139976498126622976, -351219561048021760

Offset

0,4

Links

Table of n, a(n) for n=0..20.

Mathematica

Tanh[ Tanh[ Log[ 1+x ] ] ]

Crossrefs

Sequence in context: A365493 A280316 A131538 * A304933 A126909 A139268

Adjacent sequences: A009817 A009818 A009819 * A009821 A009822 A009823

Keyword

sign,easy

Author

R. H. Hardin

Extensions

Extended with signs by Olivier Gérard, Mar 15 1997

Status

approved