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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A093593 n! times sum of Farey fractions of order n. 2
1, 3, 15, 84, 660, 4680, 47880, 463680, 5261760, 59875200, 858211200, 11256537600, 183697113600, 2833294464000, 47730114432000, 847372990464000, 17250840262656000, 329722245844992000, 7359528574734336000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

Eric Weisstein's World of Mathematics, Farey Sequence..

EXAMPLE

Multiplication of n-th-order positive Farey fractions by n! gives the integer sequence A002088(n), for n>=1. Arrange them in rows:

1

1 2

2 3 4 6

6 8 12 16 18 24

The sum over row 4 is a(4)=84.

MATHEMATICA

Farey[n_] := Union[ Flatten[ Join[{0}, Table[a/b, {b, n}, {a, b}]]]]; Table[n!Plus @@ Farey[n], {n, 0, 20}] (* Robert G. Wilson v, Apr 06 2004 *)

CROSSREFS

Cf. A002088, A092824, A093594.

Sequence in context: A005809 A067122 A202336 * A212201 A011900 A118342

Adjacent sequences:  A093590 A093591 A093592 * A093594 A093595 A093596

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 03 2004

EXTENSIONS

More terms from Robert G. Wilson v, Apr 06 2004

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 4 13:05 EST 2020. Contains 338923 sequences. (Running on oeis4.)