// find amicable pairs p1, p2 where each is equal to the other's proper divisor sum

MAX_NUMBER = 20000
pdSum = [1] * ( MAX_NUMBER + 1 )    // table of proper divisors
for i in range( 2, MAX_NUMBER )
    for j in range( i + i, MAX_NUMBER, i )
        pdSum[ j ] += i
    end for
end for
// find the amicable pairs up to 20 000
ap = []
for p1 in range( 1, MAX_NUMBER - 1 )
    pdSumP1 = pdSum[ p1 ]
    if pdSumP1 > p1 and pdSumP1 <= MAX_NUMBER and pdSum[ pdSumP1 ] == p1 then
        print str( p1 ) + " and " + str( pdSumP1 ) + " are an amicable pair"
    end if
end for