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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, 1, 2, 6, 3, 60, 360, 2520, 1680, 15120, 2800, 831600, 9979200, 9266400, 165110400, 27243216000, 27243216000, 102918816000, 793945152000, 355537728000, 150849578880000, 22174888095360000, 3049047113112000, 43155743754816000 (list; graph; refs; listen; history; text; internal format)
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 * A077750 A332253 A247493

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

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Last modified May 9 07:36 EDT 2021. Contains 343692 sequences. (Running on oeis4.)