The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A205562 Least positive integer j such that n divides (2k)!-(2j)!, where k, as in A205561, is the least number for which there is such a j. 0
1, 1, 2, 2, 3, 2, 4, 2, 3, 3, 1, 2, 7, 4, 3, 3, 9, 3, 1, 3, 4, 1, 2, 2, 3, 7, 5, 4, 2, 3, 1, 4, 3, 9, 4, 3, 19, 1, 7, 3, 4, 4, 1, 3, 3, 2, 2, 3, 4, 3, 9, 7, 1, 5, 3, 4, 5, 2, 12, 3, 4, 1, 4, 4, 7, 3, 1, 9, 2, 4, 2, 3, 2, 19, 3, 5, 6, 7, 2, 3, 5, 4, 12, 4, 9, 1, 2, 3, 4, 3, 7, 2, 6, 2, 5, 4, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
For a guide to related sequences, see A204892.
LINKS
EXAMPLE
1 divides (2*2)!-(2*1)! -> k=2, j=1
2 divides (2*2)!-(2*1)! -> k=2, j=1
3 divides (2*3)!-(2*2)! -> k=3, j=2
4 divides (2*3)!-(2*2)! -> k=3, j=2
5 divides (2*4)!-(2*3)! -> k=4, j=3
MATHEMATICA
s = Table[(2n)!, {n, 1, 120}];
lk = Table[NestWhile[# + 1 &, 1,
Min[Table[Mod[s[[#]] - s[[j]], z], {j, 1, # - 1}]] =!= 0 &], {z, 1, Length[s]}]
Table[NestWhile[# + 1 &, 1,
Mod[s[[lk[[j]]]] - s[[#]], j] =!= 0 &], {j, 1, Length[lk]}]
(* Peter J. C. Moses, Jan 27 2012 *)
CROSSREFS
Sequence in context: A141829 A111336 A083902 * A217984 A196437 A106491
KEYWORD
nonn
AUTHOR
Clark Kimberling, Feb 01 2012
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 01:34 EDT 2024. Contains 372900 sequences. (Running on oeis4.)