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A009806
Expansion of tanh(tan(log(1+x))).
0
0, 1, -1, 2, -6, 16, 0, -792, 13776, -200552, 2855880, -41436352, 620388912, -9606956592, 153409074000, -2508503487232, 41503122145920, -680444083117184, 10600133081473152, -140189781816392448, 819083424632851200
OFFSET
0,4
MATHEMATICA
Tanh[ Tan[ Log[ 1+x ] ] ]
CROSSREFS
Sequence in context: A009711 A009586 A009487 * A151708 A356370 A355096
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Extended with signs by Olivier Gérard, Mar 15 1997
STATUS
approved