Spiral Golf

gistfile1.py

n,r,c=31,range,'x '
s=map(r,[n]*n)
def f(x):
    q=r(x,n-x)
    for i in q:
        for j in q:s[i][j]=c[x%2]
for i in r(0,n/2,2):f(i),f(i+1);s[i+2][i+1],s[i+1][i]=c
for r in s:print ' '.join(r)

https://gist.github.com/yosun/b21d82c1f97af8d3a0fa

chieu's functional math: https://gist.github.com/KirarinSnow/a2abcbfeda046a62b29d

Shrunken to 99 chars!!!

Now 93 chars!!!

Now 87!!

If the size (an odd integer) is read in through stdin, then 95 chars.