OFFSET
1,2
COMMENTS
FORMULA
EXAMPLE
For n = 99:
- 99 = 11^1 * 7^0 * 5^0 * 3^2 * 2^0,
- the list of exponents is: 1 0 0 2 0,
- compressing consecutive values, we obtain: 1 0 2 0,
- so a(99) = 7^1 * 5^0 * 3^2 * 2^0 = 63.
PROG
(PARI) a(n) = { my (v=1, e=-1, k=0); forprime (p=2, oo, if (n==1, return (v), if (e!=e=valuation(n, p), v*=prime(k++)^e); n/=p^e)) }
CROSSREFS
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Jul 23 2022
STATUS
approved