A009642 - OEIS

A009642

Expansion of tan(log(1+x))*cos(x).

0, 1, -1, 1, -12, 75, -555, 4863, -48832, 552293, -6948765, 96252429, -1455398604, 23851683999, -421107222263, 7967875766875, -160844272481760, 3450332758515657, -78376836240861273, 1879454111175884697

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OFFSET

0,5

LINKS

Table of n, a(n) for n=0..19.

FORMULA

a(n) ~ n! * (-1)^(n+1) * cos(1-exp(-Pi/2)) / ((exp(Pi/2)-1) * (1-exp(-Pi/2))^n). - Vaclav Kotesovec, Jan 23 2015

MATHEMATICA

Tan[ Log[ 1+x ] ]*Cos[ x ]

CoefficientList[Series[Cos[x]*Tan[Log[1 + x]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jan 23 2015 *)

CROSSREFS

Sequence in context: A053310 A368530 A006235 * A051104 A044199 A044580

Adjacent sequences: A009639 A009640 A009641 * A009643 A009644 A009645

KEYWORD

sign,easy

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved