A057642 (Product k^k) * (Sum 1/k^k) where both the sum and product are over those positive integers k that divide n.

1, 5, 28, 1284, 3126, 6485292, 823544, 21541946368, 10847773719, 156290000012500, 285311670612, 14847746691430172786688, 302875106592254, 45756121633729931379676, 38327538543365478600000, 397378771500072999738379599872, 827240261886336764178

Offset

1,2

Links

Alois P. Heinz, Table of n, a(n) for n = 1..200

Example

The positive divisors of 4 are 1, 2, 4. So a(4) = 1^1 *2^2 *4^4 *(1/1^1 +1/2^2 +1/4^4) = 1284.

Maple

with(numtheory):
a:= n-> (l-> mul(k^k, k=l)*add(1/k^k, k=l))(divisors(n)):
seq(a(n), n=1..20);  # Alois P. Heinz, May 22 2015

Mathematica

a[n_] := Function[l, Product[k^k, {k, l}] * Sum[1/k^k, {k, l}]] @ Divisors[n]; Array[a, 20] (* Jean-François Alcover, Mar 23 2017 *)

Crossrefs

Sequence in context: A359739 A344464 A348393 * A125137 A348350 A132550

Adjacent sequences: A057639 A057640 A057641 * A057643 A057644 A057645

Keyword

nonn

Author

Leroy Quet, Oct 11 2000

Status

approved