OFFSET
1,1
COMMENTS
a(n) is the number of lattice points on a sphere around (0,0,0) with r^2 = A071609(n).
LINKS
Hugo Pfoertner, Table of n, a(n) for n = 1..189
FORMULA
EXAMPLE
A sphere with radius 1 has 6 lattice points on its surface, so a(1)=6. A sphere with r=sqrt(2) passes through 12 lattice points of the shape (1,1,0), so a(2)=12. A sphere with r=sqrt(5) passes through 24 lattice points with shape (2,1,0), so a(3)=24. A sphere with r=sqrt(9) passes through 6 lattice points of shape (3,0,0) and through 24 lattice points of shape (2,2,1), so a(4)=6+24=30.
CROSSREFS
KEYWORD
nonn
AUTHOR
Hugo Pfoertner, May 25 2002
STATUS
approved