A339990 - OEIS

%I #12 Nov 17 2024 18:04:15

%S 2,28,54,126,152,250,344,370,468,686,730,756,854,1072,1332,1358,1456,

%T 1458,1674,2060,2198,2224,2322,2540,2662,2926,3376,3402,3500,3528,

%U 3718,4104,4394,4706,4914,4940,5038,5256,5572,5642,6244,6750,6860,6886,6984,7110,7202

%N Sums of two odd cubes.

%e 28 is in the sequence since 1^3 + 3^3 = 1 + 27 = 28, with 1 and 27 both odd.

%t Table[If[Sum[Mod[i, 2] Mod[n - i, 2] (Floor[i^(1/3)] - Floor[(i - 1)^(1/3)]) (Floor[(n - i)^(1/3)] - Floor[(n - i - 1)^(1/3)]), {i, Floor[n/2]}] > 0, n, {}], {n, 1200}] // Flatten

%t Union[Total/@Tuples[Range[1,25,2]^3,2]] (* _Harvey P. Dale_, Nov 17 2024 *)

%o (Python)

%o def aupto(lim):

%o   ocs = [k**3 for k in range(1, int(lim**(1/3)+2), 2)]

%o   return sorted(set(c1+c2 for c1 in ocs for c2 in ocs if c1+c2 <= lim))

%o print(aupto(7202)) # _Michael S. Branicky_, Feb 28 2021

%Y Cf. A010057.

%K nonn

%O 1,1

%A _Wesley Ivan Hurt_, Dec 25 2020