OFFSET
1,3
COMMENTS
In the table output, one can observe constant diagonals (or lines in the square output). The indices of these are: 1, 3, 4, 6, 7, 8, 12, 13, ... (see A002191). And the corresponding values are: 1, 2, 3, 5, 4, 7, 6, 9, ... (see A002192). - Michel Marcus, Dec 19 2013
FORMULA
Min{x; Mod[sigma[x], n]=r}, r=1..n, n=1, ...
EXAMPLE
Triangle begins
1;
1,3;
1,7,2;
1,5,2,3;
1,4,2,3,8; ...
MATHEMATICA
{k=0, s=0, fl=1}; Table[Print["#"]; Table[fl=1; Print[{r, m}]; Do[s=Mod[DivisorSigma[1, n], m]; If[(s==r)&&(fl==1), Print[n]; fl=0], {n, 1, 150000}], {r, 0, m-1}], {m, 1, 25}]
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Labos Elemer, Aug 26 2002
STATUS
approved