OFFSET
1,1
COMMENTS
a(19) > 5*10^11. - Giovanni Resta, May 05 2020
MATHEMATICA
q[n_] := Divisible[Sum[j * Floor[n/j], {j, 1, n}], n + 1]; Select[Range[100], q] (* Amiram Eldar, May 03 2021 *)
PROG
(PARI) for(k=1, 1e4, if(sum(j=1, k, k\j*j)%(k+1)==0, print1(k", ")))
(PARI) s=0; for(k=1, 1e7, s+=sigma(k); if(s%(k+1)==0, print1(k", ")))
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, May 04 2020
EXTENSIONS
a(16)-a(18) from Giovanni Resta, May 05 2020
STATUS
approved