tle: 'Combination (binomial)',
            latex: `\\binom{n}{k}= {n \\choose k} = {^n}C_k = \\frac{n!}{k!(n-k)!}`,
          },
          {
            pic: 'genfrac-1.gif',
            title: 'genfrac in a <kbd>\\scriptstyle</kbd>',
            latex: `x^{\\binom{n}{k}}`,
          },
          {
            title: '<kbd>\\atopwithdelims</kbd>',
            class: '',
            latex: `{n \\atopwithdelims ()0}`,
          },
          {
            title: 'Only one infix per group',
            comment: