A025287 Numbers that are the sum of 2 nonzero squares in exactly 4 ways.

1105, 1625, 1885, 2125, 2210, 2405, 2465, 2665, 3145, 3250, 3445, 3485, 3625, 3770, 3965, 4225, 4250, 4420, 4505, 4625, 4745, 4810, 4930, 5125, 5185, 5330, 5365, 5785, 5945, 6205, 6290, 6305, 6409, 6500, 6565, 6625, 6890, 6970, 7085, 7225, 7250, 7345

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Donovan Johnson, Table of n, a(n) for n = 1..1000
• Index entries for sequences related to sums of squares

Programs

Mathematica

nn = 7345; t = Table[0, {nn}]; lim = Floor[Sqrt[nn - 1]]; Do[num = i^2 + j^2; If[num <= nn, t[[num]]++], {i, lim}, {j, i}]; Flatten[Position[t, 4]] (* T. D. Noe, Apr 07 2011 *)
nz4Q[n_]:=Count[IntegerPartitions[n,{2}],?(FreeQ[#,0]&&AllTrue[Sqrt[#],IntegerQ]&)]==4; Select[Range[7500],nz4Q] (* _Harvey P. Dale, Jul 23 2024 *)