A244668 -id:A244668 - cp's OEIS frontend

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

Jaroslav Krizek, Jul 04 2014

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

For numerators see A244668.

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

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

[Denominator((&*[d: d in Divisors(n)]) / (&+[d: d in Divisors(n)])): n in [1..1000]]

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

a(n) = 1 for numbers from A145551 (numbers n such that product of divisors of n / sum of divisors of n is an integer).

A244670 Product of divisors of n / sum of divisors of n for n such that product of divisors of n is divisible by sum of divisors of n.

Original entry on oeis.org

1, 3, 392, 11250, 131769, 1568294784, 501126, 119439360000000, 6566468639062500, 39226324511250000, 15780962, 162778775259375000, 2966827112704, 22417760034702144000000000000, 1801703513076518898, 30261936128, 3531477204506250000, 5876813016539072244

Offset: 1

Jaroslav Krizek, Jul 04 2014

nonn

			For n = 4; A145551(4) = 30; A244668(30) = 11250.

Cf. A007955, A000203, A145551, A244668, A244669.

[Numerator((&*[d: d in Divisors(n)]) / (&+[d: d in Divisors(n)])): n in [1..10000] | Denominator((&*[d: d in Divisors(n)]) / (&+[d: d in Divisors(n)])) eq 1]

a(n) = A007955(A145551(n)) / A000203(A145551(n)) = A244668(A145551(n)).

cp's OEIS Frontend

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

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