OFFSET
1,2
COMMENTS
Does a(n)=sigma(n^2) for a finite number of values of n (1,2,3,4,6,8,12,18,24,60)? See A074964.
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..750
MAPLE
A074963 := proc(n)
a := 0 ;
for x from 1 to n do
for y from 1 to x do
a := max(a, numtheory[sigma](x*y)) ;
end do:
end do;
a ;
end proc: # R. J. Mathar, Sep 27 2011
MATHEMATICA
a[n_] := Module[{m = 0}, Do[m = Max[m, DivisorSigma[1, x*y]], {x, 1, n}, {y, 1, x}]; m]; Array[a, 50] (* Jean-François Alcover, Feb 12 2018 *)
PROG
(PARI) a(n)=vecmax(matrix(n, n, x, y, sigma(x*y)))
(Haskell)
a074963 n = maximum [a000203 (x*y) | x <- [1..n], y <- [x..n]]
-- Reinhard Zumkeller, Nov 14 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Oct 05 2002
STATUS
approved