BEGIN {

    A[0] = "&"

    for(i=1;i<=11;i++) {

	A[i] = "\\" A[i-1]

    }

## A[] holds  & \& \\& \\\& \\\\& ...

}

{

    for(i=0; i <= 11 ; i++) {

        x = $0 

        sub(/B/, A[i], x)

	y = gensub(/B/, A[i], "1", $0)

	print i, x, y

    }

}