A025376 Numbers that are the sum of 4 distinct nonzero squares in exactly 1 way.
30, 39, 46, 50, 51, 54, 57, 62, 63, 65, 66, 70, 71, 74, 75, 79, 81, 84, 85, 86, 87, 91, 93, 98, 106, 107, 109, 113, 116, 117, 118, 120, 121, 122, 125, 127, 131, 133, 137, 139, 140, 145, 149, 161, 163, 164, 173, 178, 180, 181, 184, 187, 196, 200, 202, 212, 216, 223, 229, 236
Offset: 1
Keywords
Programs
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Mathematica
With[{nn=60},Take[Union[Transpose[Select[Tally[Total/@Subsets[Range[nn]^2,{4}]], #[[2]]==1&]][[1]]],nn]] (* Harvey P. Dale, Mar 10 2015 *)
Formula
{n: A025443(n) = 1}. - R. J. Mathar, Jun 15 2018