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Like A019279 but using anti-divisors. sigma*^2(n)=sigma*(sigma*(n))=2n, where sigma*(n) is the sum of the anti-divisors of n.
Table of n, a(n) for n=1..16.
for n from 1 do
if A066417(A066417(n)) = 2*n then
end do: # R. J. Mathar, Oct 02 2011
Cf. A019279, A066417.
Sequence in context: A012504 A012689 A098632 * A009807 A220991 A165388
Adjacent sequences: A192272 A192273 A192274 * A192276 A192277 A192278
Paolo P. Lava, Jun 28 2011
a(9)-a(16) from Donovan Johnson, Sep 22 2011