A047686 Denominators of coefficients in Taylor series for log(tan(x)/x).

1, 3, 90, 2835, 18900, 66825, 1915538625, 127702575, 186080895000, 350813659321125, 7656647326453125, 3018906660144375, 1211517431782539131250, 144228265688397515625, 564653660170076273671875, 84913182070036240111050234375, 499921764568178729658131250000

Offset

0,2

References

CRC Standard Mathematical Tables and Formulae, 30th ed. 1996, p. 42.

Links

Table of n, a(n) for n=0..16.

Index entries for Bernoulli numbers B(2n)

Formula

A047685(n)/a(n) = 2^(2n) *(2^(2n-1) -1) *abs(B(2n)) / ((2n)! *n).

Example

(1/3)*x^2 + (7/90)*x^4 + (62/2835)*x^6 + (127/18900)*x^8 + (146/66825)*x^10 + ...

Crossrefs

Cf. A047685, B(2n)= A027641(2n) / A027642(2n).

Sequence in context: A254083 A103305 A097235 * A013304 A013298 A013302

Adjacent sequences: A047683 A047684 A047685 * A047687 A047688 A047689

Keyword

nonn,easy,frac

Author

N. J. A. Sloane

Status

approved