A372512 - OEIS

%I #4 May 04 2024 15:00:37

%S 0,0,0,1,1,1,1,1,1,1,1,4,4,4,4,4,4,4,4,7,7,7,7,7,7,7,7,11,11,11,11,11,

%T 11,11,11,17,17,17,17,17,17,17,17,20,20,20,20,20,20,20,20,26,26,26,26,

%U 26,26,26,26,35,35,35,35,35,35,35,35,38,38,38,38,38,38,38,38,45,45,45,45,45,45

%N Number of solutions to x^2 + y^2 + z^2 <= n, where x, y, z are positive odd integers.

%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>

%t nmax = 80; CoefficientList[Series[EllipticTheta[2, 0, x^4]^3/(8 (1 - x)), {x, 0, nmax}], x]

%Y Cf. A000606, A008437, A085121, A117609, A211639, A349610, A372511.

%K nonn

%O 0,12

%A _Ilya Gutkovskiy_, May 04 2024