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A025340 Numbers that are the sum of 3 distinct nonzero squares in exactly 2 ways. 1
62, 69, 74, 77, 86, 89, 90, 94, 98, 105, 117, 122, 125, 129, 131, 138, 141, 150, 154, 155, 158, 165, 166, 170, 179, 181, 195, 197, 201, 203, 210, 213, 217, 218, 225, 227, 229, 233, 238, 241, 242, 246, 248, 249, 250, 259, 273, 274, 275, 276, 282, 296, 297, 301, 308, 310 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..1777

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]=2, [$1..N]); # Robert Israel, Jan 03 2016

CROSSREFS

Sequence in context: A095565 A095553 A024804 * A048127 A047823 A294738

Adjacent sequences:  A025337 A025338 A025339 * A025341 A025342 A025343

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified January 15 20:47 EST 2019. Contains 319184 sequences. (Running on oeis4.)