A025287 - OEIS

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

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OFFSET

1,1

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..1000

Index entries for sequences related to sums of squares

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 *)

CROSSREFS

Sequence in context: A257759 A025295 A025314 * A025305 A052155 A097102

Adjacent sequences: A025284 A025285 A025286 * A025288 A025289 A025290

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved