A067655 Denominators of the coefficients in exp(2x/(1-x)) power series.

1, 1, 3, 3, 15, 45, 315, 315, 2835, 14175, 155925, 467775, 6081075, 3869775, 638512875, 638512875, 10854718875, 8881133625, 1856156927625, 9280784638125, 194896477400625, 2143861251406875, 2595200462229375

Offset

1,3

Comments

Differs from A049606 at positions enumerated by A097324.

References

K. Knopp, Theory and application of infinite series, Dover, p. 547.

O. Perron, Über das infinitäre Verhalten der Koeffizienten einer gewissen Potenzreihe, Archiv d. Math. u. Phys. (3), Vol. 22, pp. 329-340, 1914.

Links

Table of n, a(n) for n=1..23.

Formula

a(n) is the denominator in Sum_{i=1..n} binomial(n-1, i-1)*2^i/i!.

Crossrefs

Cf. A067654.

Sequence in context: A160639 A280781 A046983 * A209430 A160624 A049606

Adjacent sequences: A067652 A067653 A067654 * A067656 A067657 A067658

Keyword

nonn,frac

Author

Benoit Cloitre, Feb 03 2002

Status

approved