A127815 a(n) = denominator of b(n), where b(1) = 2, b(n) = b(n-1) - 1/b(n-1).

1, 2, 6, 30, 330, 257070, 128005692870, 23279147893155496537470, 388475314992168993748220639081347493631827670, 102339769648127358726761918460732576814168548432921287355299929744910591862606847215978930

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Formula

For n >= 2, a(n) = a(n-1)*A127814(n-1).

Example

A127814/A127815 = 2, 3/2, 5/6, -11/30, 779/330, 497941/257070, 181860254581/128005692870, ...

Mathematica

f[l_List] := Append[l, l[[ -1]] - 1/l[[ -1]]]; Denominator[Nest[f, {2}, 10]] (* Ray Chandler, Feb 07 2007 *)

Crossrefs

Cf. A127814.

Sequence in context: A333373 A064847 A242996 * A054934 A001684 A076926

Adjacent sequences: A127812 A127813 A127814 * A127816 A127817 A127818

Keyword

easy,frac,nonn

Author

Leroy Quet, Jan 30 2007

Extensions

Extended by Ray Chandler, Feb 07 2007

Status

approved