%I #16 Feb 15 2014 02:42:15

%S 25,100,169,225,289,400,625,676,841,900,1156,1225,1369,1521,1600,1681,

%T 2025,2500,2601,2704,2809,3025,3364,3600,3721,4225,4624,4900,5329,

%U 5476,5625,6084,6400,6724,7225,7569,7921,8100,8281,9025,9409,10000,10201

%N Square numbers which are sums of 2 distinct nonzero squares.

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

%F a(n) = A009003(n)^2.

%e 25 = 5^2 = 4^2 + 3^2, and so 25 is in the sequence.

%e 100 = 10^2 = 8^2 + 6^2, and so 100 is in the sequence.

%e 169 = 13^2 = 12^2 + 5^2, and so 169 is in the sequence.

%t c = {}; Do[Do[k = a^2 + b^2; If[IntegerQ[Sqrt[k]], AppendTo[c, k]], {a, 1, b - 1}], {b, 200}]; Union[c] (* _Artur Jasinski_ *)

%t Select[Range[100]^2, Length[PowersRepresentations[#, 2, 2]] > 1 &] (* _Alonso del Arte_, Feb 11 2014 *)

%o (PARI) select(n->for(k=1,sqrtint(n\2),if(issquare(n-k^2), return(n>k^2)));0, vector(100,i,i^2)) \\ _Charles R Greathouse IV_, Jul 02 2013

%Y Cf. A000404, A000415, A009003.

%K nonn

%O 1,1

%A _Artur Jasinski_, Oct 25 2007