A004440 - OEIS

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

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OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

Index entries for sequences related to sums of squares

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:

select(i -> V[i] = 0, [$1..N]); # Robert Israel, Dec 31 2015

CROSSREFS

Cf. A004432 (complement).

Sequence in context: A272477 A056651 A022772 * A026495 A004437 A298534

Adjacent sequences: A004437 A004438 A004439 * A004441 A004442 A004443

KEYWORD

nonn

AUTHOR

N. J. A. Sloane

STATUS

approved