A004440 Numbers that are not the sum of 3 distinct nonzero squares.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 27, 28, 31, 32, 33, 34, 36, 37, 39, 40, 43, 44, 47, 48, 51, 52, 55, 57, 58, 60, 63, 64, 67, 68, 71, 72, 73, 76, 79, 80, 82, 85, 87, 88, 92, 95, 96, 97, 99, 100, 102, 103, 108, 111, 112, 119, 123, 124, 127, 128, 130, 132, 135, 136, 143, 144, 148, 151, 156, 159, 160, 163, 167, 172, 175, 176

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to sums of squares

Crossrefs

Cf. A004432 (complement).

Programs

Maple

N:= 1000: # to get all terms <= N
V:= Vector(N):
for x from 1 to floor(sqrt(N/3)) do
  for y from x+1 to floor(sqrt((N-x^2)/2)) do
    zs:= [$(y+1).. floor(sqrt(N-x^2-y^2))];
    V[map(z -> x^2 + y^2 + z^2, zs)]:= 1;
  od
od:
select(i -> V[i] = 0, [$1..N]); # Robert Israel, Dec 31 2015