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.

A105556 Triangle, read by rows, such that column n equals the row sums of A001263^n, which is the n-th matrix power of the Narayana triangle A001263, for n>=0.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 5, 3, 1, 1, 14, 12, 4, 1, 1, 42, 57, 22, 5, 1, 1, 132, 303, 148, 35, 6, 1, 1, 429, 1743, 1144, 305, 51, 7, 1, 1, 1430, 10629, 9784, 3105, 546, 70, 8, 1, 1, 4862, 67791, 90346, 35505, 6906, 889, 92, 9, 1, 1, 16796, 448023, 885868, 444225, 99156
Offset: 0

Views

Author

Paul D. Hanna, Apr 14 2005

Keywords

Comments

Column 1 is the Catalan numbers A000108 (offset 1).

Examples

			Triangle begins:
  1;
  1,    1;
  1,    2,     1;
  1,    5,     3,     1;
  1,   14,    12,     4,     1;
  1,   42,    57,    22,     5,    1;
  1,  132,   303,   148,    35,    6,   1;
  1,  429,  1743,  1144,   305,   51,   7,  1;
  1, 1430, 10629,  9784,  3105,  546,  70,  8, 1;
  1, 4862, 67791, 90346, 35505, 6906, 889, 92, 9, 1;
  ...
From _Paul D. Hanna_, Feb 01 2009: (Start)
G.f. for rows n=0..3 are:
B(x) = 1 + x + x^2/3 + x^3/18 + x^4/180 + x^5/2700 + ... + x^n/[n!*(n+1)!/2^n] + ...
B(x)^2 = 1 + 2*x + 5*x^2/3 + 14*x^3/18 + 42*x^4/180 + ... + A000108(n)*x^n/[n!*(n+1)!/2^n] + ...
B(x)^3 = 1 + 3*x +12*x^2/3 + 57*x^3/18 +303*x^4/180 + ... + A103370(n)*x^n/[n!*(n+1)!/2^n] + ...
B(x)^4 = 1 + 4*x +22*x^2/3 +148*x^3/18+1144*x^4/180 + 9784*x^5/2700 + 90346*x^5/56700 + ... (End)
		

Crossrefs

Cf. A001263, A105557 (row sums), A103370 (column 2).
Cf. A155926. - Paul D. Hanna, Feb 01 2009

Programs

  • PARI
    {T(n,k)=local(N=matrix(n+1,n+1,m,j,if(m>=j, binomial(m-1,j-1)*binomial(m,j-1)/j))); sum(j=0,n-k,(N^k)[n-k+1,j+1])}
    
  • PARI
    {T(n,k)=local(B=sum(j=0,n-k,x^j/(j!*(j+1)!/2^j))+x*O(x^(n-k))); polcoeff(B^(k+1),n-k)*(n-k)!*(n-k+1)!/2^(n-k)} \\ Paul D. Hanna, Feb 01 2009

Formula

From Paul D. Hanna, Feb 01 2009: (Start)
G.f. of column k = B(x)^(k+1) where B(x) = Sum_{n>=0} x^n/[n!*(n+1)!/2^n];
T(n,K) = [x^(n-k)] B(x)^(k+1) * (n-k)!*(n-k+1)!/2^(n-k) for n >= k >= 0. (End)

A112338 Triangle read by rows, generated from A001263.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 5, 1, 1, 4, 12, 14, 1, 1, 5, 22, 57, 42, 1, 1, 6, 35, 148, 303, 132, 1, 1, 7, 51, 305, 1144, 1743, 429, 1, 8, 70, 546, 3105, 9784, 10629, 1430, 1
Offset: 0

Views

Author

Gary W. Adamson, Sep 04 2005

Keywords

Comments

Rows of the array are row sums of n-th powers of the Narayana triangle; e.g., row 1 = A000108: (1, 2, 5, 14, 42, ...); row 2 = row sums of the Narayana triangle squared (A103370): (1, 3, 12, 57, 303, ...), etc.

Examples

			In the array, antidiagonal terms (1, 3, 5, 1) become row 3 of the triangle.
First few rows of the array:
  1, 1,  1,   1,    1,     1, ...
  1, 2,  5,  14,   42,   132, ...
  1, 3, 12,  57,  303,  1743, ...
  1, 4, 22, 148, 1144,  9784, ...
  1, 5, 35, 305, 3105, 35505, ...
First few rows of the triangle:
  1;
  1, 1;
  1, 2,  1;
  1, 3,  5,   1;
  1, 4, 12,  14,   1;
  1, 5, 22,  57,  42,   1;
  1, 6, 35, 148, 303, 132, 1;
		

Crossrefs

Formula

Let M be the infinite lower triangular Narayana triangle (A001263). Perform M^n * [1 0 0 0 ...] getting an array. Take antidiagonals of the array which become rows of the triangle A112338.
Showing 1-2 of 2 results.