|
|
A205564
|
|
Least positive integer j such that n divides 2k!-2j!, where k, as in A205563, is the least number for which there is such a j.
|
|
0
|
|
|
1, 1, 3, 2, 1, 3, 1, 2, 3, 1, 2, 3, 4, 1, 5, 4, 1, 3, 3, 5, 3, 2, 1, 4, 5, 4, 6, 3, 4, 5, 2, 4, 4, 1, 7, 3, 6, 3, 4, 5, 5, 3, 8, 2, 6, 1, 4, 4, 7, 5, 3, 4, 2, 6, 6, 7, 3, 4, 2, 5, 8, 2, 7, 4, 13, 4, 5, 3, 4, 7, 7, 6, 4, 6, 5, 3, 11, 4, 9, 5, 9, 5, 3, 3, 5, 8, 4, 4, 8, 6, 13, 4, 11, 4, 13, 4
(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*4!-2*3! -> k=4, j=3
4 divides 2*3!-2*2! -> k=3, j=2
5 divides 2*3!-2*1! -> k=3, j=1
|
|
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]}]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|