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

%I

%S 1,3,6,11,18,26,37,50,63,80,96,115,136,159,186,210,239,268,301,336,

%T 368,407,444,487,526,574,619,664,717,764,820,875,930,989,1047,1112,

%U 1175,1238,1307,1375,1444,1521,1592,1669,1745,1828,1907,1988,2073,2161,2252

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

%F a(n) = [x^(n^3)] (1/(1 - x))*(Sum_{k>=0} x^(k^3))^2. - _Ilya Gutkovskiy_, Apr 20 2018

%o (Python)

%o for a in range(99):

%o n = a*a*a

%o k = 0

%o for x in range(99):

%o s = x*x*x

%o if s>n: break

%o for y in range(99):

%o sy = s + y*y*y

%o if sy>n: break

%o k+=1

%o print(str(k), end=',')

%o (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 nonn

%O 0,2

%A _Alex Ratushnyak_, Apr 01 2013

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Last modified March 20 05:18 EDT 2023. Contains 361358 sequences. (Running on oeis4.)