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Numbers that are the sum of 2 distinct nonzero squares in exactly 3 ways.
4

%I #17 Dec 08 2013 06:30:13

%S 325,425,650,725,845,850,925,1025,1300,1325,1445,1450,1525,1690,1700,

%T 1825,1850,2050,2225,2425,2525,2600,2650,2725,2825,2873,2890,2900,

%U 2925,3050,3125,3380,3400,3425,3650,3700,3725,3757,3825,3925,4100,4205,4325

%N Numbers that are the sum of 2 distinct nonzero squares in exactly 3 ways.

%H Donovan Johnson, <a href="/A025304/b025304.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>

%t nn = 4325; t = Table[0, {nn}]; lim = Floor[Sqrt[nn - 1]]; Do[num = i^2 + j^2; If[num <= nn, t[[num]]++], {i, lim}, {j, i - 1}]; Flatten[Position[t, 3]] (* _T. D. Noe_, Apr 07 2011 *)

%K nonn

%O 1,1

%A _David W. Wilson_