A128192 a(n) = denominator of b(n), where b(1)=1, b(n+1) = sum{k=1 to n} {b(n+1-k)/k} ({x} is the fractional part of x).

1, 1, 2, 6, 3, 60, 360, 2520, 1680, 15120, 2800, 831600, 9979200, 9266400, 165110400, 27243216000, 27243216000, 102918816000, 793945152000, 355537728000, 150849578880000, 22174888095360000, 3049047113112000, 43155743754816000

Offset

1,3

Links

Table of n, a(n) for n=1..24.

Mathematica

f[l_List] := Block[{n = Length[l]}, Append[l, Sum[ FractionalPart[l[[n + 1 - k]]/k], {k, n}]]]; Denominator[Nest[f, {1}, 23]] (* Ray Chandler, Feb 26 2007 *)

Crossrefs

Cf. A128191.

Sequence in context: A206429 A101819 A177761 * A354375 A077750 A332253

Adjacent sequences: A128189 A128190 A128191 * A128193 A128194 A128195

Keyword

frac,nonn

Author

Leroy Quet, Feb 17 2007

Extensions

Extended by Ray Chandler, Feb 26 2007

Status

approved