A070239 a(1) = 1; a(2) = 2; a(n) = sigma_a[n-2] (a[n-1]), n > 2, where sigma_k (n) denotes the sum of the k-th powers of the divisors of n.

1, 2, 3, 10, 1134, 3520155193849864644872367756250

Offset

1,2

Links

Table of n, a(n) for n=1..6.

Example

a(4) = sigma_a(2) (a(3)) = sigma_2 (3) = 1^2 + 3^2 = 10.

Crossrefs

Sequence in context: A218271 A128125 A351775 * A002443 A111788 A238455

Adjacent sequences: A070236 A070237 A070238 * A070240 A070241 A070242

Keyword

nonn

Author

Joseph L. Pe, May 08 2002

Status

approved