/* Fill array with Van Eck sequence */
proc nonrec make_eck([*] word eck) void:
    int i, j, max;
    max := dim(eck,1)-1;
    for i from 0 upto max do eck[i] := 0 od;

    for i from 0 upto max-1 do
        j := i - 1;
        while j >= 0 and eck[i] ~= eck[j] do
            j := j - 1
        od;
        if j >= 0 then
            eck[i+1] := i - j
        fi
    od
corp

/* Print eck[0..9] and eck[990..999] */
proc nonrec main() void:
    word i;
    [1000] word eck;
    make_eck(eck);

    for i from 0 upto 9 do write(eck[i]:4) od;
    writeln();
    for i from 990 upto 999 do write(eck[i]:4) od;
    writeln()
corp