The Eulerian polynomials of the second kind are defined as (see for example here)

E_n(x) = \sum_{m\ge0} \left\langle\!\!\left\langle n\atop  m\right\rangle\!\!\right\rangle  x^m .

I would like to use \genfrac to display this formula (similar as \genfrac is used to display the Eulerian numbers). Is this possible?


2 Answers 2


The following example takes the double brackets from package MnSymbol and uses \genfrac. An alternative would be a simple matrix environment.


      <-6>  MnSymbolE5
     <6-7>  MnSymbolE6
     <7-8>  MnSymbolE7
     <8-9>  MnSymbolE8
     <9-10> MnSymbolE9
    <10-12> MnSymbolE10
    <12->   MnSymbolE12}{}
      <-6>  MnSymbolE-Bold5
     <6-7>  MnSymbolE-Bold6
     <7-8>  MnSymbolE-Bold7
     <8-9>  MnSymbolE-Bold8
     <9-10> MnSymbolE-Bold9
    <10-12> MnSymbolE-Bold10
    <12->   MnSymbolE-Bold12}{}


  E_n(x) = \sum_{m\ge0} \Eulerian{n}{m} x^m



This solution uses \genfrac although not exclusively; however it does avoid \atop and works with MathJax.

\sum_{m\ge0}\left\langle\!\!\!\genfrac<>{0pt}{}{n}{m}\!\!\!\right\rangle x^{m} 

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