A166715 Irregular triangle read by rows: row n lists nonzero quadratic residues modulo the n-th term of A123239.

1, 1, 1, 3, 4, 5, 9, 1, 3, 4, 9, 10, 12, 1, 3, 4, 7, 9, 10, 11, 12, 16, 21, 25, 26, 27, 28, 30, 33, 34, 36, 1, 2, 4, 5, 8, 9, 10, 16, 18, 20, 21, 23, 25, 31, 32, 33, 36, 37, 39, 40, 1, 3, 4, 5, 7, 9, 12, 15, 16, 17, 19, 20, 21, 22, 25, 26, 27

Offset: 1

Author

A.K. Devaraj, Oct 20 2009

Keywords

• nonn
• tabf

Examples

			Triangle starts:
1;
1;
1,3,4,5,9;
1,3,4,9,10,12;
...
Modulo A123239(3)=11, the quadratic residues are 1,3,4,5,9.
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Quadratic Residue.

Crossrefs

Cf. A046071, A063987, A123239.

Programs

Mathematica

MangammalQ[p_]:=Block[{k=3},While[k>2,k=Mod[3k,p]];k!=2];
A123239=Select[Prime[Range[17]],MangammalQ];
A166715=Flatten[Union[Mod[Range[Floor[#/2]]^2,#]]&/@A123239] (* Ray Chandler, Jul 21 2011 *)

Extensions

Edited by N. J. A. Sloane, Oct 22 2009

Edited by Charles R Greathouse IV, Oct 28 2009

Edited, corrected and extended by Ray Chandler, Jul 21 2011