The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A009702

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A009702

Expansion of tan(tan(x))/cosh(x) (odd powers only).
(history; published version)

#11 by Vaclav Kotesovec at Fri Jan 23 14:41:52 EST 2015

STATUS

editing

approved

#10 by Vaclav Kotesovec at Fri Jan 23 14:41:46 EST 2015

FORMULA

a(n) ~ (2*n-1)! * 8 / ((4+Pi^2) * cosh(arctan(Pi/2)) * arctan(Pi/2)^(2*n)). - Vaclav Kotesovec, Jan 23 2015

#9 by Vaclav Kotesovec at Fri Jan 23 14:40:30 EST 2015

NAME

Expansion of tan(tan(x))/cosh(x) (odd powers only).

OFFSET

0,1,3

MATHEMATICA

nn = 20; Table[(CoefficientList[Series[Sech[x]*Tan[Tan[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Jan 23 2015 *)

EXTENSIONS

Offset changed to 1 by Vaclav Kotesovec, Jan 23 2015

STATUS

approved

editing

#8 by N. J. A. Sloane at Mon Jan 27 09:13:00 EST 2014

EXTENSIONS

Extended and signs tested Mar 15 1997 by _Olivier GerardGérard_.

Discussion

Mon Jan 27

09:13

OEIS Server: https://oeis.org/edit/global/2111

#7 by Russ Cox at Sat Mar 31 12:34:56 EDT 2012

AUTHOR

_R. H. Hardin (rhhardin(AT)att.net)_

Discussion

Sat Mar 31

12:34

OEIS Server: https://oeis.org/edit/global/875

#6 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009

KEYWORD

nonn,new

nonn

AUTHOR

R. H. Hardin (rhhrhhardin(AT)cadenceatt.comnet)

#5 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

KEYWORD

nonn,new

nonn

AUTHOR

R. H. Hardin (rhh@research.att(AT)cadence.com)

EXTENSIONS

Extended and signs tested 03/97 Mar 15 1997 by Olivier Gerard.

#4 by N. J. A. Sloane at Sat Dec 11 03:00:00 EST 1999

MATHEMATICA

Tan[ Tan[ x ] ]/Cosh[ x ] (* Odd Part *)

KEYWORD

nonn,new

nonn

#3 by N. J. A. Sloane at Sun Jun 14 03:00:00 EDT 1998

NAME

Expansion of tan(tan($x$))/cosh($x$).

DATA

1, 1, 57, 1657, 136977, 14004945, 2219125001, 457176874377, 123849671844513, 41945147421378337, 17490738249607542873, 8778749876346904238105, 5226971507061600220653233, 3640737476966979742943568113

REFERENCES

MATHEMATICA

Tan[Tan[x]]/Cosh[x] (* Odd Part *)

KEYWORD

,new

nonn

EXTENSIONS

Extended and signs tested 03/97 by Olivier Gerard.

#2 by N. J. A. Sloane at Wed Dec 11 03:00:00 EST 1996

REFERENCES

KEYWORD

,new