A170911 Write exp(-x) = Product_{n>=1} (1 + g_n x^n); a(n) = denominator(g_n).

1, 2, 3, 8, 5, 72, 7, 128, 81, 800, 11, 13824, 13, 6272, 30375, 32768, 17, 419904, 19, 20480000, 750141, 247808, 23, 1528823808, 15625, 1384448, 1594323, 5035261952, 29, 30233088000000, 31, 2147483648, 235782657, 37879808, 1313046875, 240734712102912, 37, 189267968

Offset

1,2

Links

Table of n, a(n) for n=1..38.

H. Gingold, H. W. Gould, and Michael E. Mays, Power Product Expansions, Utilitas Mathematica 34 (1988), 143-161.

Example

-1, 1/2, 1/3, 3/8, 1/5, 13/72, 1/7, 27/128, 8/81, 91/800, 1/11, ...

Maple

L:=100; t1:=exp(-x); t0:=series(t1, x, L): g:=[]; M:=40; t2:=t0:
for n from 1 to M do t3:=coeff(t2, x, n); t2:=series(t2/(1+t3*x^n), x, L); g:=[op(g), t3]; od: g;

Crossrefs

Cf. A170910 (numerators).

Sequence in context: A128779 A112283 A136182 * A067911 A243103 A051696

Adjacent sequences: A170908 A170909 A170910 * A170912 A170913 A170914

Keyword

nonn,frac

Author

N. J. A. Sloane, Jan 30 2010

Status

approved