This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A074625 Triangular array T(n,k) (n >= 1, 1 <= k <= n) read by rows, where T(n,k) = smallest number x such that Mod[sigma[x],n]=k. 1

%I

%S 1,1,3,1,7,2,1,5,2,3,1,4,2,3,8,1,7,2,3,2401,5,1,29,2,3,6,5,4,1,10,2,3,

%T 9,5,4,7,1,19,2,3,13,5,4,7,10,1,6,2,3,8,5,4,7,18,19,1,9,2,3,24,5,4,7,

%U 16,21,43,1,13,2,3,2401,5,4,7,49,31213,9604,6,1,8,2,3,10,5,4,7,33,22

%N Triangular array T(n,k) (n >= 1, 1 <= k <= n) read by rows, where T(n,k) = smallest number x such that Mod[sigma[x],n]=k.

%F Min{x; Mod[sigma[x], n]=r}, r=1..n, n=1, ...

%e 1; 1,3; 1,7,2; 1,5,2,3; 1,4,2,3,8; ...

%t {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}]

%Y Cf. A000203, A028982, A074384-A074386, A072461, A072462, A072862.

%K nonn,tabl

%O 1,3

%A Labos E. (labos(AT)ana.sote.hu), Aug 26 2002

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .