A134422 Square numbers which are sums of 2 distinct nonzero squares.

25, 100, 169, 225, 289, 400, 625, 676, 841, 900, 1156, 1225, 1369, 1521, 1600, 1681, 2025, 2500, 2601, 2704, 2809, 3025, 3364, 3600, 3721, 4225, 4624, 4900, 5329, 5476, 5625, 6084, 6400, 6724, 7225, 7569, 7921, 8100, 8281, 9025, 9409, 10000, 10201

Offset: 1

Author

Artur Jasinski, Oct 25 2007

Keywords

• nonn

Examples

			25 = 5^2 = 4^2 + 3^2, and so 25 is in the sequence.
100 = 10^2 = 8^2 + 6^2, and so 100 is in the sequence.
169 = 13^2 = 12^2 + 5^2, and so 169 is in the sequence.
		

Links

• Index entries for sequences related to sums of squares

Crossrefs

Cf. A000404, A000415, A009003.

Programs

Mathematica

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 *)
Select[Range[100]^2, Length[PowersRepresentations[#, 2, 2]] > 1 &] (* Alonso del Arte, Feb 11 2014 *)

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

Formula

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