OFFSET
0,2
LINKS
David A. Corneth, Table of n, a(n) for n = 0..1500
David A. Corneth, Pari prog
FORMULA
a(n) = [x^(n^3)] (1/(1 - x))*(Sum_{k>=0} x^(k^3))^3. - Ilya Gutkovskiy, Apr 20 2018
EXAMPLE
For n=1, the four solutions are {0,0,0}, {0,0,1}, {0,1,0} and {1,0,0}, so a(1)=4.
PROG
(Python)
for a in range(99):
n = a*a*a
k = 0
for x in range(99):
s = x*x*x
if s>n: break
for y in range(99):
sy = s + y*y*y
if sy>n: break
for z in range(99):
sz = sy + z*z*z
if sz>n: break
k+=1
print(str(k), end=', ')
(PARI) a(n) = n++; p = Pol((1/(1 - x))*sum(k=0, n, x^(k^3))^3 + O(x^(n^3))); polcoeff(p, (n-1)^3); \\ Michel Marcus, Apr 21 2018
(PARI) See PARI link \\ David A. Corneth, May 22 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Apr 01 2013
STATUS
approved