

A175368


Number of integer 4tuples (x,y,z,u) satisfying x^3+y^3+z^3+u^3 = n, n <= x,y,z,u <= n.


1



1, 8, 24, 32, 16, 0, 0, 0, 8, 48, 96, 64, 0, 0, 0, 0, 24, 96, 96, 0, 0, 0, 0, 0, 32, 64, 0, 8, 48, 96, 64, 0, 16, 0, 0, 48, 192, 192, 0, 0, 0, 0, 0, 96, 192, 0, 0, 0, 0, 0, 0, 64, 0, 0, 24, 96, 96, 0, 0, 0, 0, 0, 96, 192, 8, 48, 96, 64, 0, 0, 96, 0, 48, 192, 192, 0, 0, 0, 0, 0, 96, 224, 64, 0
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,2


COMMENTS

A variant of A000118 with cubes instead of squares.


LINKS

Table of n, a(n) for n=0..83.


FORMULA

Conjecture: g.f. ( 1+2*sum_{j>=1} x^(j^3) )^4.


EXAMPLE

a(1) = 8 counts (x,y,z,u) = (1,0,0,0), (0,1,0,0), (0,0,1,0), (0,0,0,1) and 4 more tuples with 1 replaced by +1.
a(2) = 24 counts (x,y,z,u) = (1,1,0,0), (1,0,1,0), (1,0,0,1), (1,0,0,1) etc, all variants where two of the 4 values are zero and the other two +1 or 1.


CROSSREFS

Sequence in context: A038524 A261394 A162829 * A000118 A096727 A028660
Adjacent sequences: A175365 A175366 A175367 * A175369 A175370 A175371


KEYWORD

nonn


AUTHOR

R. J. Mathar, Apr 24 2010


STATUS

approved



