|
| |
|
|
A066570
|
|
Product of numbers <= n that have a prime factor in common with n.
|
|
2
| |
|
|
1, 2, 3, 8, 5, 144, 7, 384, 162, 19200, 11, 1244160, 13, 4515840, 1458000, 10321920, 17, 75246796800, 19, 278691840000, 1080203040, 899245670400, 23, 16686729658368000, 375000, 663152807116800, 7142567040, 209964381084057600, 29, 1229978843118305280000000
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| Empty product, 1, for n = 1.
a(p) = p if p is a prime.
|
|
|
FORMULA
| a(n) = n!/A001783(n).
|
|
|
EXAMPLE
| a(7) = 7, a(9) = 3*6*9 = 162.
|
|
|
MAPLE
| A066570 := proc(n) local i; mul(i, i=remove(k->igcd(n, k)=1, [$1..n])) end: # Peter Luschny, Oct 11 2011
|
|
|
CROSSREFS
| Cf. A001783.
Sequence in context: A170911 A067911 A051696 * A073656 A047930 A073875
Adjacent sequences: A066567 A066568 A066569 * A066571 A066572 A066573
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Dec 19 2001
|
| |
|
|
