OFFSET
1,2
COMMENTS
Sequence is probably finite.
The next term in the sequence, if it exists, is larger than 40000. - Stewart Gordon, Sep 27 2011
Conjecture: subsequence of A066522, implying finiteness. - Reinhard Zumkeller, Nov 14 2011
FORMULA
MAPLE
with(numtheory): s := proc(n) option remember: return sigma(n): end: a:= proc(n) option remember: if(n=0)then return 0: fi: return max(a(n-1), seq(s(x*n), x=1..n)): end: for n from 1 to 100 do if(a(n)=s(n^2))then printf("%d, ", n): end: od: # Nathaniel Johnston, Sep 26 2011
PROG
(Haskell)
a074964 n = a074964_list !! (n-1)
a074964_list = filter (\x -> a074963 x == a065764 x) [1..]
-- Reinhard Zumkeller, Nov 14 2011
(PARI) isok(k) = vecmax(setbinop((x, y)->sigma(x*y), [1..k])) == sigma(k^2); \\ Michel Marcus, Feb 03 2022
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Benoit Cloitre, Oct 05 2002
STATUS
approved