A025341 Numbers that are the sum of 3 distinct nonzero squares in exactly 3 ways.

101, 110, 126, 134, 146, 149, 173, 174, 182, 185, 186, 221, 222, 237, 245, 251, 257, 278, 286, 294, 302, 305, 306, 309, 315, 318, 334, 338, 342, 349, 353, 354, 366, 377, 402, 404, 409, 410, 430, 440, 453, 454, 467, 481, 490, 502, 504, 514, 515, 517, 526, 529, 531, 536

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..1690
• Index entries for sequences related to sums of squares

Programs

Maple

N:= 10^6; # to get all terms <= N
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]=3,[$1..N]); # Robert Israel, Jan 03 2016