<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mi mathvariant="bold-script">O</mml:mi>
<mml:mo mathvariant="bold">(</mml:mo>
<mml:mi mathvariant="bold">N</mml:mi>
<mml:mo mathvariant="bold">)</mml:mo>
</mml:math>