##TI-BASIC, 23 bytes
TI-BASIC, 23 bytes
sum(seq(Σ(X²+Y²=Ans,X,-Ans,Ans),Y,-Ans,Ans
Pretty straightforward. Σ(
is summation.
Strangely, sum(seq(sum(seq(
throws an ERR:ILLEGAL NEST
, and so does Σ(Σ(
, but sum(seq(Σ(
is fine. I chose to put the Σ(
on the inside to save a close-paren.