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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. 0
1, 2, 3, 10, 1134, 3520155193849864644872367756250 (list; graph; refs; listen; history; text; internal format)
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: A184163 A218271 A128125 * A002443 A111788 A238455

Adjacent sequences:  A070236 A070237 A070238 * A070240 A070241 A070242

KEYWORD

nonn

AUTHOR

Joseph L. Pe, May 08 2002

STATUS

approved

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Last modified March 23 16:52 EDT 2019. Contains 321432 sequences. (Running on oeis4.)