|
|
A063917
|
|
Smallest k such that k!!! is a multiple of n.
|
|
3
|
|
|
1, 2, 3, 4, 5, 6, 7, 8, 6, 5, 11, 12, 13, 7, 15, 8, 17, 6, 19, 8, 21, 11, 23, 12, 20, 13, 9, 7, 29, 15, 31, 14, 33, 17, 10, 12, 37, 19, 39, 8, 41, 21, 43, 11, 15, 23, 47, 18, 28, 20, 51, 13, 53, 9, 11, 10, 57, 29, 59, 15, 61, 31, 21, 16, 13, 33, 67, 17, 69
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
REFERENCES
|
F. Smarandache, "Some problems in number theory", Student Conference, University of Craiova, Department of Mathematics, 1979.
|
|
LINKS
|
|
|
EXAMPLE
|
a(16) = 8 because 8!!! = 8*(8 - 3)*(8 - 6) = 8*5*2 which is divisible by 16 and 8 is the smallest integer with this property.
|
|
MATHEMATICA
|
f[n_] := Product[k, {k, n, 1, -3}]; a[n_] := Module[{k = 1}, While[! Divisible[ f[k], n], k++]; k]; Array[a, 100] (* Amiram Eldar, Dec 08 2018 *)
With[{tbl=Table[Times@@Range[k, 1, -3], {k, 100}]}, Table[Position[tbl, _?(Divisible[ #, n]&), 1, 1], {n, 70}]]//Flatten (* Harvey P. Dale, Feb 11 2020 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Mike Antholy (mikeantholy(AT)yahoo.ca), Aug 31 2001
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|