OFFSET
1,16
COMMENTS
A223728(n) has a(n) different primitive representations as sum of four distinct nonzero squares, n>=1.
FORMULA
a(n) = k if there are k different solutions for A223728(n) = sum(s(j)^2, j=1..4), with 0 < s(1) < s(2) < s(3) < s(4) and gcd(s(1),s(2),s(3),s(4)) = 1.
EXAMPLE
CROSSREFS
KEYWORD
nonn
AUTHOR
Wolfdieter Lang, Mar 27 2013
STATUS
approved