A156036 - OEIS

A156036

Numerators in expansion of log(z^2/(cosh(z)-cos(z))).

0, -1, 1, -691, 3617, -174611, 236364091, -3392780147, 7709321041217, -26315271553053477373, 261082718496449122051, -2530297234481911294093, 5609403368997817686249127547, -61628132164268458257532691681, 354198989901889536240773677094747, -1215233140483755572040304994079820246041491

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OFFSET

0,4

REFERENCES

V. Mangulis, Handbook of Series, Academic Press, 1965, p. 76.

LINKS

Table of n, a(n) for n=0..15.

FORMULA

log(z^2/(cosh(z)-cos(z))) = Sum_{ n >= 1 } (-1)^n*B_{2n}*(2z^2)^(2n)/((4n)!2n).

a(n)=Numerator((-1)^n * Zeta(4n)/(Zeta(2n)*Pi^(2n)). - Enrique Pérez Herrero, Jun 20 2012

EXAMPLE

log(z^2/(cosh(z)-cos(z))) = -(1/360)*z^4+(1/302400)*z^8-(691/122594472000)*z^12+(3617/333456963840000)*z^16+...