OFFSET
1,1
FORMULA
a(n) = A000396(n)^2
EXAMPLE
a(2)=784 because the second perfect number is 28 and 28^2=784.
MATHEMATICA
Select[Range[9000], DivisorSigma[1, #]== 2*# &]^2 (* G. C. Greubel, Oct 03 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Oct 30 2007
EXTENSIONS
More terms from Olaf Voß, Feb 13 2008
STATUS
approved