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A098219
a(n) = floor(sigma(sigma(n))/n) = floor(A051027(n)/n).
6
1, 2, 2, 2, 2, 4, 2, 3, 1, 3, 2, 4, 1, 4, 4, 2, 2, 3, 2, 4, 3, 4, 2, 7, 1, 3, 3, 4, 2, 6, 2, 3, 3, 3, 3, 3, 1, 4, 3, 5, 2, 6, 1, 5, 3, 4, 2, 4, 1, 2, 3, 3, 2, 6, 3, 6, 3, 4, 2, 8, 1, 4, 3, 2, 3, 6, 1, 4, 3, 5, 2, 4, 1, 3, 2, 4, 3, 6, 2, 4, 1, 3, 2, 6, 3, 3, 4, 6, 2, 6, 2, 5, 2, 4, 3, 7, 1, 2, 3, 2, 2, 5, 2, 5, 4
OFFSET
1,2
LINKS
EXAMPLE
For n=10, a(10) = floor(sigma(sigma(10))/10) = floor(sigma(18)/10) = floor(39/10) = 3.
MATHEMATICA
Table[Floor[Nest[DivisorSigma[1, #] &, n, 2]/n], {n, 120}] (* Michael De Vlieger, Mar 02 2017 *)
PROG
(PARI) a(n) = sigma(sigma(n))\n; \\ Michel Marcus, Oct 07 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 25 2004
STATUS
approved