A128191 - OEIS

A128191

a(n) = numerator 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, 0, 1, 5, 4, 67, 487, 4553, 4307, 42113, 7657, 2770303, 33997961, 38742337, 583876093, 102330518993, 144962489299, 446086957889, 4381834446001, 2161313089987, 845959774632353, 114556945039764949, 19211766762696841

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OFFSET

1,4

LINKS

Table of n, a(n) for n=1..23.

MATHEMATICA

f[l_List] := Block[{n = Length[l]}, Append[l, Sum[ FractionalPart[l[[n + 1 - k]]/k], {k, n}]]]; Numerator[Nest[f, {1}, 22]] (* Ray Chandler, Feb 26 2007 *)

CROSSREFS

Cf. A128192.

Sequence in context: A192344 A181613 A264880 * A375410 A186639 A266668

Adjacent sequences: A128188 A128189 A128190 * A128192 A128193 A128194

KEYWORD

frac,nonn

AUTHOR

Leroy Quet, Feb 17 2007

EXTENSIONS

Extended by Ray Chandler, Feb 26 2007

STATUS

approved