msubsupBsize1

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <msup>
    <mi>x</mi>
    <mn>1</mn>
  </msup>
  <mo>+</mo>
  <msup>
    <mi>x</mi>
    <mi>a</mi>
  </msup>
  <mo>+</mo>
  <msup>
    <mi>H</mi>
    <mi>a</mi>
  </msup>
  <mo>+</mo>
  <msup>
    <mi>H</mi>
    <mn>1</mn>
  </msup>
  <mo>+</mo>
  <msubsup>
    <mi>x</mi>
    <mn>1</mn>
    <mn>2</mn>
  </msubsup>
  <mo>+</mo>
  <msubsup>
    <mi>x</mi>
    <mi>a</mi>
    <mn>2</mn>
  </msubsup>
  <mo>+</mo>
  <msubsup>
    <mi>x</mi>
    <mn>1</mn>
    <mi>x</mi>
  </msubsup>
  <mo>+</mo>
  <msubsup>
    <mi>x</mi>
    <mi>a</mi>
    <mi>x</mi>
  </msubsup>
  <mo>+</mo>
  <msubsup>
    <mi>H</mi>
    <mn>1</mn>
    <mn>2</mn>
  </msubsup>
  <mo>+</mo>
  <msubsup>
    <mi>H</mi>
    <mi>a</mi>
    <mn>2</mn>
  </msubsup>
  <mo>+</mo>
  <msubsup>
    <mi>H</mi>
    <mn>1</mn>
    <mi>x</mi>
  </msubsup>
  <mo>+</mo>
  <msubsup>
    <mi>H</mi>
    <mi>a</mi>
    <mi>x</mi>
  </msubsup>
</math>

Author: Design Science, Inc. (E. Cannon, E. Tabacman, R.Miner)