|
|
A085081
|
|
Group the natural numbers such that the product of the terms of the n-th group has a divisor with the same prime signature as that of the product of the terms of the (n-1)-th group. (1), (2), (3), (4), (5,6,7,8), (9,10,11,12,13,14),... Sequence contains the product of the terms of the groups.
|
|
0
|
|
|
1, 2, 3, 4, 1680, 2162160, 586051200, 5967561600, 1220096908800, 33371339479827148800, 10221346459144248675287040000, 1065516759202418135010355181075171069914644480000000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
In most cases when n >3 a(n) is a multiple of a(n-1). Question: is it true for all n >3.
For 6 <= n <= 13, a(n) doesn't divide a(n+1). I believe this also holds for all larger n. - David Wasserman, Jan 18 2005
|
|
LINKS
|
|
|
EXAMPLE
|
a(5) = 2162160 = 2^4*3^3*5*7*11*13 and a(4) = 1680= 2^4*3*5*7.
a(4) itself divides a(5).
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|