function skidpatchchart(),

gears = [30:66];
cogs = 4:30;
fprintf('    cogs');
for k = 1:length(cogs);
    fprintf('%4d',cogs(k));
end
fprintf('\ngears\n');
for j = 1:length(gears),
    fprintf('%4d    ',gears(j));
    for k = 1:length(cogs),
        fprintf('%4d',skidpatch(gears(j),cogs(k)));
    end
    fprintf('\n');
end

function sp = skidpatch(g,c),
% this is totally non optimal code, but i had fun writing it

primes = setdiff(1:100,unique(repmat(2:50,49,1).*repmat([2:50]',1,49)));
primes = primes(2:end);

sp = c;
while (g>primes(1)),
    if g/primes(1) == floor(g/primes(1)) & sp/primes(1) == floor(sp/primes(1)),
        sp = sp/primes(1);
        g = g/primes(1);
    else
        primes = primes(2:end);
    end
end
        


    cogs   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
gears
  30       2   1   1   7   4   3   1  11   2  13   7   1   8  17   3  19   2   7  11  23   4   5  13   9  14  29   5
  31       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  32       1   5   3   7   1   9   5  11   3  13   7  15   1  17   9  19   5  21  11  23   3  25  13  27   7  29  15
  33       4   5   2   7   8   3  10   1   4  13  14   5  16  17   6  19  20   7   2  23   8  25  26   9  28  29  10
  34       2   5   3   7   4   9   5  11   6  13   7  15   8   1   9  19  10  21  11  23  12  25  13  27  14  29  15
  35       4   1   6   1   8   9   2  11  12  13   2   3  16  17  18  19   4   3  22  23  24   5  26  27   4  29   6
  36       1   5   1   7   2   1   5  11   1  13   7   5   4  17   1  19   5   7  11  23   2  25  13   3   7  29   5
  37       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  38       2   5   3   7   4   9   5  11   6  13   7  15   8  17   9   1  10  21  11  23  12  25  13  27  14  29  15
  39       4   5   2   7   8   3  10  11   4   1  14   5  16  17   6  19  20   7  22  23   8  25   2   9  28  29  10
  40       1   1   3   7   1   9   1  11   3  13   7   3   2  17   9  19   1  21  11  23   3   5  13  27   7  29   3
  41       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  42       2   5   1   1   4   3   5  11   2  13   1   5   8  17   3  19  10   1  11  23   4  25  13   9   2  29   5
  43       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  44       1   5   3   7   2   9   5   1   3  13   7  15   4  17   9  19   5  21   1  23   6  25  13  27   7  29  15
  45       4   1   2   7   8   1   2  11   4  13  14   1  16  17   2  19   4   7  22  23   8   5  26   3  28  29   2
  46       2   5   3   7   4   9   5  11   6  13   7  15   8  17   9  19  10  21  11   1  12  25  13  27  14  29  15
  47       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  48       1   5   1   7   1   3   5  11   1  13   7   5   1  17   3  19   5   7  11  23   1  25  13   9   7  29   5
  49       4   5   6   1   8   9  10  11  12  13   2  15  16  17  18  19  20   3  22  23  24  25  26  27   4  29  30
  50       2   1   3   7   4   9   1  11   6  13   7   3   8  17   9  19   2  21  11  23  12   1  13  27  14  29   3
  51       4   5   2   7   8   3  10  11   4  13  14   5  16   1   6  19  20   7  22  23   8  25  26   9  28  29  10
  52       1   5   3   7   2   9   5  11   3   1   7  15   4  17   9  19   5  21  11  23   6  25   1  27   7  29  15
  53       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  54       2   5   1   7   4   1   5  11   2  13   7   5   8  17   1  19  10   7  11  23   4  25  13   1  14  29   5
  55       4   1   6   7   8   9   2   1  12  13  14   3  16  17  18  19   4  21   2  23  24   5  26  27  28  29   6
  56       1   5   3   1   1   9   5  11   3  13   1  15   2  17   9  19   5   3  11  23   3  25  13  27   1  29  15
  57       4   5   2   7   8   3  10  11   4  13  14   5  16  17   6   1  20   7  22  23   8  25  26   9  28  29  10
  58       2   5   3   7   4   9   5  11   6  13   7  15   8  17   9  19  10  21  11  23  12  25  13  27  14   1  15
  59       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  60       1   1   1   7   2   3   1  11   1  13   7   1   4  17   3  19   1   7  11  23   2   5  13   9   7  29   1
  61       4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30
  62       2   5   3   7   4   9   5  11   6  13   7  15   8  17   9  19  10  21  11  23  12  25  13  27  14  29  15
  63       4   5   2   1   8   1  10  11   4  13   2   5  16  17   2  19  20   1  22  23   8  25  26   3   4  29  10
  64       1   5   3   7   1   9   5  11   3  13   7  15   1  17   9  19   5  21  11  23   3  25  13  27   7  29  15
  65       4   1   6   7   8   9   2  11  12   1  14   3  16  17  18  19   4  21  22  23  24   5   2  27  28  29   6
  66       2   5   1   7   4   3   5   1   2  13   7   5   8  17   3  19  10   7   1  23   4  25  13   9  14  29   5