1<?xml version='1.0'?> 2<!DOCTYPE html PUBLIC '-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN' 3 'http://www.w3.org/TR/MathML2/dtd/xhtml-math11-f.dtd' 4 [<!ENTITY mathml 'http://www.w3.org/1998/Math/MathML'>]> 5<html xmlns='http://www.w3.org/1999/xhtml'> 6<head><title>trigamma1</title> 7<!-- MathML created with MathCast Equation Editor version 0.89 --> 8</head> 9<body> 10<math xmlns="http://www.w3.org/1998/Math/MathML" display="block"> 11 <mrow> 12 <msup> 13 <mi>ψ</mi> 14 <mfenced> 15 <mrow> 16 <mn>1</mn> 17 </mrow> 18 </mfenced> 19 </msup> 20 <mfenced> 21 <mrow> 22 <mi>x</mi> 23 </mrow> 24 </mfenced> 25 <mo>=</mo> 26 <munderover> 27 <mo>∑</mo> 28 <mrow> 29 <mi>k</mi> 30 <mo>=</mo> 31 <mn>0</mn> 32 </mrow> 33 <mi>∞</mi> 34 </munderover> 35 <mfrac> 36 <mn>1</mn> 37 <mrow> 38 <msup> 39 <mfenced> 40 <mrow> 41 <mi>k</mi> 42 <mo>+</mo> 43 <mi>x</mi> 44 </mrow> 45 </mfenced> 46 <mn>2</mn> 47 </msup> 48 </mrow> 49 </mfrac> 50 <mo>=</mo> 51 <mfrac> 52 <mrow> 53 <mo>∂</mo> 54 <mi>ψ</mi> 55 <mfenced> 56 <mrow> 57 <mi>x</mi> 58 </mrow> 59 </mfenced> 60 </mrow> 61 <mrow> 62 <mo>∂</mo> 63 <mi>x</mi> 64 </mrow> 65 </mfrac> 66 </mrow> 67</math> 68</body> 69</html>