OFFSET
1,2
COMMENTS
More precisely the denominator equals the product of the largest squarefree divisors of composite numbers up to n.
FORMULA
a(1)=1, a(n) = a(n-1)*n/(n's prime factors).
EXAMPLE
a(4) = (1*4*6*8*9)/((2)*(2*3)*(2)*(3)) = 24.
MAPLE
MATHEMATICA
PrimeFactors[ n_Integer ] := Flatten[ Table[ # [ [ 1 ] ], {1} ] & /@ FactorInteger[ n ] ]; a[ 1 ] := 1; a[ n_ ] := a[ n ] = a[ n - 1 ]*n / Times @@ PrimeFactors[ n ]; Union[ Table[ a[ n ], {n, 1, 63} ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 26 2003
EXTENSIONS
Edited and extended by Robert G. Wilson v, Jun 27 2003
STATUS
approved