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A244669
Denominators of (product of divisors of n / sum of divisors of n).
2
1, 3, 4, 7, 6, 1, 8, 15, 13, 9, 12, 7, 14, 6, 8, 31, 18, 13, 20, 21, 32, 9, 24, 5, 31, 21, 40, 1, 30, 1, 32, 63, 16, 27, 48, 91, 38, 15, 56, 9, 42, 2, 44, 21, 26, 18, 48, 31, 57, 93, 8, 49, 54, 5, 72, 15, 80, 45, 60, 7, 62, 24, 104, 127, 84, 1, 68, 63, 32, 9
OFFSET
1,2
COMMENTS
Denominators of (A007955(n) / A000203(n)).
For numerators see A244668.
FORMULA
a(n) = 1 for numbers from A145551 (numbers n such that product of divisors of n / sum of divisors of n is an integer).
EXAMPLE
a(8) = 15 because A007955(8) / A000203(8) = 64 / 15.
PROG
(Magma)[Denominator((&*[d: d in Divisors(n)]) / (&+[d: d in Divisors(n)])): n in [1..1000]]
(PARI) a007955(n)=if(issquare(n, &n), n^numdiv(n^2), n^(numdiv(n)/2)) ;
a(n) = denominator(a007955(n)/sigma(n)); \\ Michel Marcus, Jul 05 2014
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Jaroslav Krizek, Jul 04 2014
STATUS
approved