A244669 Denominators of (product of divisors of n / sum of divisors of n).

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

Author

Jaroslav Krizek, Jul 04 2014

Keywords

• nonn
• frac

Comments

Denominators of (A007955(n) / A000203(n)).

For numerators see A244668.

Examples

			a(8) = 15 because A007955(8) / A000203(8) = 64 / 15.
		

Crossrefs

Cf. A007955, A000203, A145551, A244668, A244670.

Programs

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

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).