cp's OEIS Frontend

A224214 Number of nonnegative solutions to x^3 + y^3 <= n^3.

%I A224214 #22 May 04 2021 08:49:25
%S A224214 1,3,6,11,18,26,37,50,63,80,96,115,136,159,186,210,239,268,301,336,
%T A224214 368,407,444,487,526,574,619,664,717,764,820,875,930,989,1047,1112,
%U A224214 1175,1238,1307,1375,1444,1521,1592,1669,1745,1828,1907,1988,2073,2161,2252
%N A224214 Number of nonnegative solutions to x^3 + y^3 <= n^3.
%F A224214 a(n) = [x^(n^3)] (1/(1 - x))*(Sum_{k>=0} x^(k^3))^2. - _Ilya Gutkovskiy_, Apr 20 2018
%o A224214 (Python)
%o A224214 for a in range(99):
%o A224214   n = a*a*a
%o A224214   k = 0
%o A224214   for x in range(99):
%o A224214     s = x*x*x
%o A224214     if s>n: break
%o A224214     for y in range(99):
%o A224214         sy = s + y*y*y
%o A224214         if sy>n: break
%o A224214         k+=1
%o A224214   print(str(k), end=',')
%o A224214 (PARI) a(n) = n++; p = Pol((1/(1 - x))*sum(k=0, n, x^(k^3))^2 + O(x^(n^3))); polcoeff(p, (n-1)^3); \\ _Michel Marcus_, Apr 21 2018
%K A224214 nonn
%O A224214 0,2
%A A224214 _Alex Ratushnyak_, Apr 01 2013