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A127815
a(n) = denominator of b(n), where b(1) = 2, b(n) = b(n-1) - 1/b(n-1).
4
1, 2, 6, 30, 330, 257070, 128005692870, 23279147893155496537470, 388475314992168993748220639081347493631827670, 102339769648127358726761918460732576814168548432921287355299929744910591862606847215978930
OFFSET
1,2
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
KEYWORD
easy,frac,nonn
AUTHOR
Leroy Quet, Jan 30 2007
EXTENSIONS
Extended by Ray Chandler, Feb 07 2007
STATUS
approved