OFFSET
1,1
COMMENTS
In 1838 Dirichlet showed that the average value of sigma(n) is (Pi^2)*(n/6) for large n (see Tattersall).
REFERENCES
Tattersall, J. "Elementary Number Theory in Nine Chapters", Cambridge University Press, 1999.
EXAMPLE
sigma(444886) = 731808 = (Pi^2 * 444886)/6 rounded off; so 444886 is a term of the sequence.
MATHEMATICA
Select[Range[10^6], Round[(Pi^2 * #)/6] == DivisorSigma[1, # ] &]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Joseph L. Pe, Jul 18 2002
EXTENSIONS
More terms from Robert G. Wilson v, Jul 27 2002
a(10)-a(17) from Giovanni Resta, Apr 03 2017
STATUS
approved