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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A168377 Riordan array (1/(1 + x), x*c(x)), where c(x) is the o.g.f. of Catalan numbers A000108.

Original entry on oeis.org

1, -1, 1, 1, 0, 1, -1, 2, 1, 1, 1, 3, 4, 2, 1, -1, 11, 10, 7, 3, 1, 1, 31, 32, 21, 11, 4, 1, -1, 101, 100, 69, 37, 16, 5, 1, 1, 328, 329, 228, 128, 59, 22, 6, 1, -1, 1102, 1101, 773, 444, 216, 88, 29, 7, 1, 1, 3760, 3761, 2659, 1558, 785, 341, 125, 37, 8, 1
Offset: 0

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Author

Philippe Deléham, Nov 24 2009

Keywords

Examples

			Triangle T(n,k) (with rows n >= 0 and columns k = 0..n) begins:
   1;
  -1,   1;
   1,   0,   1;
  -1,   2,   1,  1;
   1,   3,   4,  2,  1;
  -1,  11,  10,  7,  3,  1;
   1,  31,  32, 21, 11,  4, 1;
  -1, 101, 100, 69, 37, 16, 5, 1;
  ...
From _Philippe Deléham_, Sep 14 2014: (Start)
Production matrix begins:
  -1, 1
   0, 1, 1
   0, 1, 1, 1
   0, 1, 1, 1, 1
   0, 1, 1, 1, 1, 1
   0, 1, 1, 1, 1, 1, 1
   0, 1, 1, 1, 1, 1, 1, 1
   0, 1, 1, 1, 1, 1, 1, 1, 1
   ... (End)
		

Crossrefs

Programs

  • PARI
    A000108(n) = binomial(2*n, n)/(n+1);
    A032357(n) = sum(k=0, n, (-1)^(n-k)*A000108(k));
    T(n, k) = if ((k==0), (-1)^n, if ((n<0) || (k<0), 0, if (k==1, A032357(n-1), if (n > k-1, T(n, k-1) - T(n-1, k-2), 0))));
    for(n=0, 10, for (k=0, n, print1(T(n, k), ", ")); print); \\ Petros Hadjicostas, Aug 08 2020

Formula

T(n,0) = (-1)^n and T(n,n) = 1.
Sum_{0 <= k <= n} T(n,k) = A032357(n).
From Petros Hadjicostas, Aug 08 2020: (Start)
T(n,k) = T(n,k-1) - T(n-1,k-2) for 2 <= k <= n with initial conditions T(n,0) = (-1)^n (n >= 0) and T(n,1) = A032357(n-1) (n >= 1).
T(n,2) = A033297(n).
T(n,n-1) = n - 2 for n >= 1.
|T(n,k)| = |A096470(n,n-k)| for 0 <= k <= n.
Bivariate o.g.f.: 1/((1 + x)*(1 - x*y*c(x))), where c(x) is the o.g.f. of A000108.
Bivariate o.g.f.: (1 - y + x*y*c(x))/((1 + x)*(1 - y + x*y^2)).
Bivariate o.g.f. of |T(n,k)|: (o.g.f. of T(n,k)) + 2*x/(1 - x^2). (End)
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