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A112288 Numerator of sum{k=1 to n} 1/s(n,k), where s(n,k) is an unsigned Stirling number of the first kind. 1
1, 2, 11, 47, 4999, 4589867, 1802849, 80995354865, 10388318700333839827, 129530631982136545940863, 460116344514106299899953231, 1272711183040784735474188752842879054737 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

4 consecutive values are primes: 2, 11, 47, 4999. - Jonathan Vos Post, Sep 08 2005

LINKS

Table of n, a(n) for n=1..12.

EXAMPLE

a(4) = 47, the numerator of 1/6 + 1/11 + 1/6 + 1 = 47/33.

The first few fractions are: 1, 2, 11/6, 47/33, 4999/4200.

MAPLE

a := n -> numer(add(1/abs(Stirling1(n, k)), k=1..n)): seq(a(n), n=1..14); # Emeric Deutsch, Sep 02 2005

MATHEMATICA

f[n_] := Sum[1/Abs[StirlingS1[n, k]], {k, n}]; Table[Numerator[f[n]], {n, 15}] (* Ray Chandler, Sep 02 2005 *)

PROG

(PARI) a(n) = numerator(sum(k=1, n, 1/abs(stirling(n, k, 1)))); \\ Michel Marcus, Aug 17 2019

CROSSREFS

Cf. A112289.

Sequence in context: A178710 A050929 A019005 * A192699 A003442 A054894

Adjacent sequences:  A112285 A112286 A112287 * A112289 A112290 A112291

KEYWORD

nonn,frac

AUTHOR

Leroy Quet, Sep 01 2005

EXTENSIONS

Extended by Emeric Deutsch and Ray Chandler, Sep 02 2005

STATUS

approved

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Last modified January 27 12:01 EST 2020. Contains 331295 sequences. (Running on oeis4.)