Amicable number calculator

Golfscript (51 50 chars)

2{.{:a,(\{.a\%!*+}/}:^~1$>{..^^={[..^](\p}*}*).}do

The core is the override of ^ as :a,(\{.a\%!*+}/ which finds the aliquot of the number on the top of the stack (call it n) by the grossly inefficient approach of considering every number from 1 to n-1 to see whether it's a factor.

C (gcc), 162, 158, 146, 138 chars

s(n){int x=1,i=2;for(;i<=sqrt(n);++i)if(n%i==0)x+=i+n/i;return x;}main(i,a){for(;;)a=s(i),((a>i)?s(a):0)==i++?printf("%d,%d\n",i-1,a):0;}

compile with gcc using gcc amic.c -o amic -lm -include math.h

To shorten it any further I suspect the algorithm would have to change.

Edits:

162->158: Consolidated the variable b into the printf conditional.

158->146: Utilized main to declare a instead of using a global var, also using implicit int of the parameter and return type for the function s(n)

146->138: Add Lowjacker's suggestion of removing the cast to double. Thanks!

Scala (120 chars):

def d(n:Int)=(1 to n-1).filter(n%_==0)
def i(x:Int,y:Int)=x!=y&&d(y).sum==x
(1 to Int.MaxValue).filter(x=>i(x,d(x).sum))