proc nonrec mertens([*] short m) void:
    word n,k;
    m[1] := 1;
    for n from 2 upto dim(m,1)-1 do
        m[n] := 1;
        for k from 2 upto n do
            m[n] := m[n] - m[n/k]
        od
    od
corp

proc nonrec main() void:
    [1001] short m;
    word x, y, eqz, crossz;

    mertens(m);
    writeln("The first 99 Mertens numbers are:");
    for y from 0 by 10 upto 90 do
        for x from 0 upto 9 do
            if x+y=0
                then write("   ")
                else write(m[x+y]:3)
            fi
        od;
        writeln()
    od;

    eqz := 0;
    crossz := 0;
    for x from 2 upto dim(m,1)-1 do
        if m[x]=0 then
            eqz := eqz + 1;
            if m[x-1]~=0 then crossz := crossz + 1 fi
        fi
    od;
    writeln("M(N) is zero ",eqz," times.");
    writeln("M(N) crosses zero ",crossz," times.")
corp