|
|
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
|
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
a(4) = sigma_a(2) (a(3)) = sigma_2 (3) = 1^2 + 3^2 = 10.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|