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.

A100335 An inverse Catalan transform of J(2n).

Original entry on oeis.org

0, 1, 4, 11, 27, 64, 149, 341, 768, 1707, 3755, 8192, 17749, 38229, 81920, 174763, 371371, 786432, 1660245, 3495253, 7340032, 15379115, 32156331, 67108864, 139810133, 290805077, 603979776, 1252698795, 2594876075, 5368709120
Offset: 0

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Author

Paul Barry, Nov 17 2004

Keywords

Comments

The g.f. is obtained from that of A002450 through the mapping g(x) -> g(x*(1-x)). A002450 may be retrieved through the mapping g(x) -> g(x*c(x)), where c(x) is the g.f. of A000108.

Crossrefs

Programs

  • Magma
    I:=[0,1,4,11]; [n le 4 select I[n] else 5*Self(n-1) -9*Self(n-2) +8*Self(n-3) -4*Self(n-4): n in [1..41]]; // G. C. Greubel, Jan 24 2023
    
  • Mathematica
    LinearRecurrence[{5,-9,8,-4}, {0,1,4,11}, 41] (* G. C. Greubel, Jan 24 2023 *)
  • SageMath
    def A100335(n): return (1/3)*((n+1)*2^n - chebyshev_U(n,1/2))
    [A100335(n) for n in range(41)] # G. C. Greubel, Jan 24 2023

Formula

G.f.: x*(1-x)/(1 - 5*x + 9*x^2 - 8*x^3 + 4*x^4).
a(n) = 5*a(n-1) - 9*a(n-2) + 8*a(n-3) - 4*a(n-4).
a(n) = Sum_{k=0..floor(n/2)} binomial(n-k, k)*(-1)^k*(4^(n-k) - 1)/3.
a(n) = (1/3)*((n+1)*2^n - A010892(n)). - Ralf Stephan, May 15 2007
Binomial transform of A042965: (1, 3, 4, 5, 7, 8, 9, 11, 12, 13, ...), also row sums of triangle A133110. - Gary W. Adamson, Sep 12 2007
a(n) = Sum_{k=0..n} A109466(n,k)*A002450(k). - Philippe Deléham, Oct 30 2008

A133109 Triangle read by rows, A042965 on the diagonal, 0 elsewhere.

Original entry on oeis.org

1, 0, 3, 0, 0, 4, 0, 0, 0, 5, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 11, 0, 0, 0, 0, 0, 0, 0, 0, 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 17
Offset: 1

Views

Author

Gary W. Adamson, Sep 12 2007

Keywords

Examples

			First few rows of the triangle:
  1;
  0, 3;
  0, 0, 4;
  0, 0, 0, 5;
  0, 0, 0, 0, 7;
  ...
		

Crossrefs

Cf. A042965, A133110 (binomial transform).

Programs

  • PARI
    row(n) = vector(n, k, if (k==n, (4*n+1)\3)); \\ Michel Marcus, Mar 07 2022

Formula

A042965: (1, 3, 4, 5, 7, 8, 9, 11, 12, 13, ...) as the diagonal of an infinite lower triangular matrix and the rest zeros.

Extensions

More terms from Michel Marcus, Mar 07 2022
Showing 1-2 of 2 results.