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<html xmlns='http://www.w3.org/1999/xhtml'>
<head><title>trigamma4</title>
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</head>
<body>
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <msup>
      <mi>&#x03C8;</mi>
      <mfenced>
        <mrow>
          <mn>1</mn>
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    <mfenced>
      <mrow>
        <mi>x</mi>
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    <mo>=</mo>
    <mfrac>
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          <mrow>
            <mi>C</mi>
            <mo>+</mo>
            <mi>R</mi>
            <mfenced>
              <mrow>
                <mi>x</mi>
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        <mi>x</mi>
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