OFFSET
1,2
COMMENTS
Appears to be almost identical to A308471.
LINKS
MathOverflow, On superabundant-like numbers
EXAMPLE
a(1) = 1 with sigma(1^2)/1^2 = 1.
a(2) = 2 with sigma(2^2)/2^2 = 7/4 > 1.
3 is not in the sequence because sigma(3^2)/3^2 = 13/9 < 7/4.
a(3) = 4 with sigma(4^2)/4^2 = 31/16 > 7/4.
MAPLE
wmax:= 0: R:= NULL:
for n from 1 to 10^6 do
w:= numtheory:-sigma(n^2)/n^2;
if w > wmax then
wmax:= w; R:= R, n;
fi;
od:
R;
MATHEMATICA
DeleteDuplicates[Table[{k, DivisorSigma[1, k^2]/k^2}, {k, 31*10^5}], GreaterEqual[#1[[2]], #2[[2]]]&][[;; , 1]] (* The program generates the first 30 terms of the sequence. To generate more increase the k constant (now set at 31*10^5) but the program may take a long time to run. *) (* Harvey P. Dale, Sep 02 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Jan 22 2021
STATUS
approved