OFFSET
1,5
COMMENTS
If the equation x^2+y^2 = n has got two solutions (x, y), (y, x) then they will be counted differently.
No solutions can exist for the values of k >= n.
a(n) is the same as A216672(n) when n is not the sum of two positive squares.
But when n is the sum of two positive squares, the ordered pairs for the equation x^2+y^2 = n count.
For example,
10 = 3^2 + 1^2.
10 = 1^2 + 3^2.
10 = 2^2 + 6*1^2.
10 = 1^2 + 9*1^2.
PROG
(PARI) for(n=1, 100, sol=0; for(k=1, n, for(x=1, n, if((issquare(n-k*x*x)&&n-k*x*x>0), sol++))); print1(sol", ")) /* V. Raman, Oct 16 2012 */
CROSSREFS
Cf. A216672 (a variant of this sequence, when the order does not matter for the equation x^2+y^2 = n, i.e. if the equation x^2+y^2 = n has got two solutions (x, y), (y, x) then they will be counted as the same).
KEYWORD
nonn
AUTHOR
V. Raman, Oct 16 2012
STATUS
approved