

A025357


Numbers that are the sum of 4 nonzero squares in exactly 1 way.


13



4, 7, 10, 12, 13, 15, 16, 18, 19, 20, 21, 22, 23, 25, 26, 27, 30, 33, 35, 38, 40, 44, 46, 48, 51, 53, 59, 62, 64, 65, 72, 80, 88, 89, 101, 104, 120, 152, 160, 176, 184, 192, 248, 256, 288, 320, 352, 416, 480, 608, 640, 704, 736, 768, 992, 1024, 1152, 1280, 1408, 1664
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OFFSET

1,1


LINKS

Robert Price, Table of n, a(n) for n = 1..95
Eric Weisstein's World of Mathematics, Square Number.
Index entries for sequences related to sums of squares


FORMULA

{n: A025428(n) = 1}.  R. J. Mathar, Jun 15 2018
A243148(a(n),4) = 1.  Alois P. Heinz, Feb 25 2019


MATHEMATICA

selQ[n_] := Length[ Select[ PowersRepresentations[n, 4, 2], Times @@ # != 0 &]] == 1; Reap[Do[If[selQ[n], Print[n]; Sow[n]], {n, 1, 2000}]][[2, 1]] (* JeanFrançois Alcover, Oct 03 2013 *)


CROSSREFS

Cf. A025428, A243148.
Sequence in context: A211642 A127958 A000414 * A222949 A144020 A047845
Adjacent sequences: A025354 A025355 A025356 * A025358 A025359 A025360


KEYWORD

nonn


AUTHOR

David W. Wilson


STATUS

approved



