cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A119828 Number triangle T(n,k)=(2n)!/(2k)!.

Original entry on oeis.org

1, 2, 1, 24, 12, 1, 720, 360, 30, 1, 40320, 20160, 1680, 56, 1, 3628800, 1814400, 151200, 5040, 90, 1, 479001600, 239500800, 19958400, 665280, 11880, 132, 1, 87178291200, 43589145600, 3632428800, 121080960, 2162160, 24024, 182, 1
Offset: 0

Views

Author

Paul Barry, May 25 2006

Keywords

Comments

Row sums are A051396(n+1). Diagonal sums are A119829. Inverse is the bi-diagonal array A119830. E.g.f. cosh(x*y)/(1-y*x^2) produces an aerated version.

Examples

			Triangle begins as:
        1,
        2,       1,
       24,      12,      1,
      720,     360,     30,    1,
    40320,   20160,   1680,   56,  1,
  3628800, 1814400, 151200, 5040, 90, 1
		

Programs

  • Mathematica
    Flatten[Table[(2n)!/(2k)!, {n, 0, 7}, {k, 0, n}]] (* James C. McMahon, Sep 23 2024 *)

Formula

Number triangle T(n,k)=[k<=n](2n)!/(2k)!
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