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.

Showing 1-2 of 2 results.

A059288 a(n) = binomial(2*n,n) mod n.

Original entry on oeis.org

0, 0, 2, 2, 2, 0, 2, 6, 2, 6, 2, 4, 2, 6, 0, 6, 2, 6, 2, 0, 6, 6, 2, 12, 2, 6, 20, 0, 2, 4, 2, 6, 9, 6, 7, 16, 2, 6, 20, 20, 2, 0, 2, 4, 0, 6, 2, 12, 2, 6, 3, 44, 2, 6, 32, 32, 39, 6, 2, 36, 2, 6, 12, 6, 5, 0, 2, 36, 66, 40, 2, 36, 2, 6, 45, 32, 0, 66, 2, 20, 20, 6, 2
Offset: 1

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Author

N. J. A. Sloane, Jan 25 2001

Keywords

Crossrefs

Programs

  • Maple
    binomial(2*n,n) mod n;
    seq(irem(binomial(2*n,n),n),n=1..83); # Zerinvary Lajos, Apr 20 2008
  • Mathematica
    Table[Mod[Binomial[2*n, n], n], {n, 1, 25}] (* G. C. Greubel, Jan 04 2017 *)
  • PARI
    a(n) = binomial(2*n, n) % n; \\ Harry J. Smith, Jun 25 2009

Formula

a(n) = Catalan(n) mod n. - Jonathan Sondow, Dec 13 2013
a(p) = 2, p an odd prime (provable using Wolstenholme's theorem). - David Trimas, Feb 11 2025

A053214 Central binomial coefficients (A000984) read mod 2n, with a(0)=1.

Original entry on oeis.org

1, 0, 2, 2, 6, 2, 0, 2, 6, 2, 16, 2, 4, 2, 20, 0, 6, 2, 24, 2, 20, 6, 28, 2, 12, 2, 32, 20, 0, 2, 4, 2, 6, 42, 40, 42, 52, 2, 44, 20, 20, 2, 0, 2, 48, 0, 52, 2, 60, 2, 56, 54, 96, 2, 60, 32, 88, 96, 64, 2, 96, 2, 68, 12, 70, 70, 0, 2, 36, 66, 40, 2, 36, 2, 80, 120, 32, 0, 144, 2, 20, 20, 88
Offset: 0

Views

Author

Asher Auel, Dec 16 1999

Keywords

Crossrefs

Programs

  • Haskell
    a053214 0 = 1
    a053214 n = a053200 (2 * n) n  -- Reinhard Zumkeller, Jan 24 2014
    
  • Mathematica
    Join[{1}, Table[Mod[Binomial[2*n, n], 2*n], {n, 1, 100}]] (* G. C. Greubel, Sep 04 2018 *)
  • PARI
    concat([1], vector(100, n, lift(Mod(binomial(2*n,n), 2*n)))) \\ G. C. Greubel, Sep 04 2018

Formula

a(n) = binomial(2*n, n) mod 2*n, with a(0)=1.
a(n) = A053200(2*n,n) for n > 0. - Reinhard Zumkeller, Jan 01 2013

Extensions

More terms from James Sellers, Dec 18 1999
Showing 1-2 of 2 results.