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A025342 Numbers that are the sum of 3 distinct nonzero squares in exactly 4 ways. 1
161, 189, 194, 209, 234, 254, 261, 270, 281, 285, 290, 293, 299, 321, 362, 365, 369, 371, 378, 386, 390, 395, 401, 405, 406, 419, 429, 449, 450, 465, 469, 477, 482, 485, 489, 491, 501, 510, 518, 534, 539, 557, 563, 570, 573, 574, 586, 589, 601, 609, 633, 644, 645, 649 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..3007

Index entries for sequences related to sums of squares

MAPLE

N:= 10^6;

A:= Vector(N):

for a from 1 to floor(sqrt(N/3)) do

  for b from a+1 to floor(sqrt((N-a^2)/2)) do

    c:= [$(b+1) .. floor(sqrt(N-a^2-b^2))]:

    v:= map(t -> a^2 + b^2 + t^2, c):

    A[v]:= map(`+`, A[v], 1)

od od:

select(t -> A[t]=4, [$1..N]); # Robert Israel, Jan 03 2016

MATHEMATICA

Sort[Transpose[Select[Tally[Total/@Subsets[Range[30]^2, {3}]], #[[2]]==4&]][[1]]] (* Harvey P. Dale, Apr 24 2013 *)

CROSSREFS

Sequence in context: A278896 A249397 A025350 * A189639 A298615 A250644

Adjacent sequences:  A025339 A025340 A025341 * A025343 A025344 A025345

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified August 20 03:33 EDT 2019. Contains 326139 sequences. (Running on oeis4.)