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A003702 Expansion of tan(x)/cosh(x).
(Formerly M5110)
5
1, -1, 21, -141, 10441, -183481, 29429661, -987318021, 276117553681, -15085947275761, 6514632269358501, -526614587249608701, 324871912636292700121, -36433570919762397948841, 30417659816002454665514541 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe and Vaclav Kotesovec, Table of n, a(n) for n = 0..240 (first 50 terms from T. D. Noe)

FORMULA

a(n) ~ (2*exp(Pi/2) + (exp(Pi) - 1)*(-1)^n) * (2*n+1)! * 2^(2*n+3) / ((1+exp(Pi)) * Pi^(2*n+2)). - Vaclav Kotesovec, Feb 16 2015

MATHEMATICA

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

nn = 20; Table[(CoefficientList[Series[Sech[x]*Tan[x], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 16 2015 *)

CROSSREFS

Sequence in context: A337899 A200987 A107731 * A221785 A301866 A101645

Adjacent sequences:  A003699 A003700 A003701 * A003703 A003704 A003705

KEYWORD

sign

AUTHOR

R. H. Hardin, Simon Plouffe

STATUS

approved

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Last modified September 16 06:18 EDT 2021. Contains 347469 sequences. (Running on oeis4.)