I am attempting to finalize the code below, but unfortunately the r1 value is maxing out at 16 while the r value is maxing out at 18.

There seems to be some issue with the way I am looping through n1, n, r1 and r, but I am unable to identify the issue.

Code:

    %MACRO s(
    p0=,    
    p1=,    
    alpha=,
    beta=,  
    usern= 
);

data s_designs;
    keep P0_s P1_s n_s n1_s n2_s r1_s r_s ESS_s PET_s;

    do n = 2 to &usern;
        do n1 = 1 to (n - 1);
            n2 = n - n1;
            do r1 = 0 to n1;
                PET_P0 = cdf('BINOMIAL', r1, &p0, n1);
                PET_P1 = cdf('BINOMIAL', r1, &p1, n1);
                 do r = (r1+1) to &usern;
                    P0_s = 1 - cdf('BINOMIAL', r, &p0, n);
                    P1_s = 1 - cdf('BINOMIAL', r, &p1, n);
                    do l = (r1 + 1) to min(n1, r);
                        if r - l > 0 and n - r > 0 then do;
                            add_P0 = pdf('BINOMIAL', l, &p0, n1) * cdf('BINOMIAL', r - l, &p0, n2);
                            add_P1 = pdf('BINOMIAL', l, &p1, n1) * cdf('BINOMIAL', r - l, &p1, n2);
                            if P0_s <= &alpha and P1_s >= 1 - &beta then do;
                                n_s = n;
                                n1_s = n1;
                                n2_s = n2;
                                r1_s = r1;
                                r_s = r;
                                PET_s = PET_P0;
                                ESS_s = n * PET_P0 + n1 * (1 - PET_P0);
                                output;
                            end;
                        end;
                    end;
                end;
            end;
        end;
    end;
run;

%MEND s;

%s(
    p0 = 0.3,
    p1 = 0.5,
    alpha = 0.1,
    beta = 0.1,
    usern = 46
);

The code is generally operating correctly except the looping iterators are not ranging from the minimum to maximum values.
In this example, r should span from 0 to 46, r1 from r1+1 to n1, and n1 from 1 to n-1.
Any insight would be greatly appreciated.