A166715 - OEIS

%I #22 May 24 2016 16:06:31

%S 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,

%T 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,

%U 5,7,9,12,15,16,17,19,20,21,22,25,26,27

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

%H G. C. Greubel, <a href="/A166715/b166715.txt">Table of n, a(n) for n = 1..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/QuadraticResidue.html">Quadratic Residue.</a>

%e Triangle starts:

%e 1;

%e 1;

%e 1,3,4,5,9;

%e 1,3,4,9,10,12;

%e ...

%e Modulo A123239(3)=11, the quadratic residues are 1,3,4,5,9.

%t MangammalQ[p_]:=Block[{k=3},While[k>2,k=Mod[3k,p]];k!=2];

%t A123239=Select[Prime[Range[17]],MangammalQ];

%t A166715=Flatten[Union[Mod[Range[Floor[#/2]]^2,#]]&/@A123239] (* _Ray Chandler_, Jul 21 2011 *)

%Y Cf. A046071, A063987, A123239.

%K nonn,tabf

%O 1,4

%A _A.K. Devaraj_, Oct 20 2009

%E Edited by _N. J. A. Sloane_, Oct 22 2009

%E Edited by _Charles R Greathouse IV_, Oct 28 2009

%E Edited, corrected and extended by _Ray Chandler_, Jul 21 2011