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.

A055451 Row sums of array in A055450.

Original entry on oeis.org

1, 4, 13, 47, 173, 678, 2735, 11378, 48279, 208410, 911571, 4031919, 17999628, 81000573, 367040404, 1673295419, 7669312343, 35319197637, 163350479756, 758406642839, 3533447414030, 16514820417166, 77412170863861
Offset: 0

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Author

Clark Kimberling, May 18 2000

Keywords

Crossrefs

Programs

  • Magma
    B:=Binomial; G:=Gamma; F:=Factorial;
    p:= func< n,k,j | B(n-2*k+j-1, j)*G(n-k+j+3/2)/(F(j)*G(n-k+3/2)*B(n-k+j+2, j)) >;
    f:= func< n,k | (n-k+1)*Binomial(n+k, k)/(n+1) >;
    function T(n,k) // T = A055450
      if k lt n/2 then return f(n-k+1, k);
      else return Round(Catalan(n-k+1)*(&+[p(n,k,j)*(-4)^j: j in [0..n]]));
      end if;
    end function;
    A055451:= func< n | (&+[T(n,k): k in [0..n]]) >;
    [A055451(n): n in [0..40]]; // G. C. Greubel, Jan 29 2024
    
  • Mathematica
    T[n_, 0]:= 1; T[n_, k_]:= T[n, k]= If[1<=kA055451[n_]:= A055451[n]= Sum[T[n,k], {k,0,n}];
    Table[A055451[n], {n,0,40}] (* G. C. Greubel, Jan 29 2024 *)
  • SageMath
    def f(n,k): return (n-k+1)*binomial(n+k, k)/(n+1)
    def T(n,k): # T = A055450
        if kA055451(n): return sum(T(n,k) for k in range(n+1))
    [A055451(n) for n in range(41)] # G. C. Greubel, Jan 30 2024

Formula

a(n) = Sum_{k=0..n} A055450(n, k). - G. C. Greubel, Jan 29 2024