login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A192986 Numerator of Sum_{i=0..n-1} B(i)/B(n), where B(i) = A000110(i) are the Bell numbers. 2
0, 1, 1, 4, 3, 6, 76, 279, 289, 5296, 26443, 71209, 820988, 5034585, 16339511, 223578344, 1606536889, 1007223253, 94951548840, 777028354999, 1652442640014, 58333928795428, 533203744952179, 2519959741699751, 49191925338483848, 495150794633289137, 2566870563431644245 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..500

R. Kaye, A Gray code for set partitions, Info. Proc. Letts., 5 (1976), 171-173.

EXAMPLE

0, 1, 1, 4/5, 3/5, 6/13, 76/203, 279/877, 289/1035, 5296/21147, 26443/115975, ...

MATHEMATICA

Table[Numerator[Sum[BellB[j], {j, 0, n-1}]/BellB[n]], {n, 0, 30}] (* G. C. Greubel, Jul 25 2019 *)

PROG

(PARI) bell(n)=sum(k=0, n, stirling(n, k, 2));

vector(30, n, n--; numerator( sum(j=0, n-1, bell(j))/bell(n)) ) \\ G. C. Greubel, Jul 25 2019

(MAGMA) [0] cat [Numerator((&+[Bell(j): j in [0..n-1]])/Bell(n)): n in [1..30]]; // G. C. Greubel, Jul 25 2019

(Sage) [numerator(sum(bell_number(j) for j in (0..n-1))/bell_number(n)) for n in (0..30)] # G. C. Greubel, Jul 25 2019

(GAP) List([0..30], n-> NumeratorRat(Sum([0..n-1], j-> Bell(j))/Bell(n)) ); # G. C. Greubel, Jul 25 2019

CROSSREFS

Cf. A000110, A192987.

Sequence in context: A276229 A077955 A077978 * A336741 A072816 A340012

Adjacent sequences:  A192983 A192984 A192985 * A192987 A192988 A192989

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Jul 13 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 6 13:24 EST 2021. Contains 349563 sequences. (Running on oeis4.)