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.

A211234 Triangle read by rows: T(n,k) is the k-th generalized Eulerian number of order n and degree 4, n >= 1.

Original entry on oeis.org

1, 2, 3, 4, 1, 4, 10, 20, 10, 4, 1, 1, 7, 27, 77, 57, 0, -57, -77, -27, -7, -1, 1, 12, 69, 272, 221, -272, -1084, -1688, -1084, -272, 221, 272, 69, 12, 1, 1, 21, 176, 936, 625, -3288, -11868, -21023, -16223, 0, 16223, 21023, 11868, 3288, -625, -936, -176, -21, -1
Offset: 1

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Author

N. J. A. Sloane, Apr 05 2012

Keywords

Examples

			Triangle begins:
  1, 2,  3,  4;
  1, 4, 10, 20, 10, 4,   1;
  1, 7, 27, 77, 57, 0, -57, -77, -27, -7, -1;
  ...
		

Crossrefs

Row sums of even rows are A047683; row sums of odd rows are zero for n > 1.

Programs

  • PARI
    T(n,r=4)={my(R=vector(n)); R[1]=[1..r]; for(n=2, n, my(u=R[n-1]); R[n]=vector(r*n-1, k, sum(j=0, r, (k - j*n)*if(k>j && k-j<=#u, u[k-j], 0)))); R}
    { my(A=T(5)); for(n=1, #A, print(A[n])) } \\ Andrew Howroyd, May 18 2020

Formula

A047683(n) = Sum_{k>=1} T(2*n, k). - Andrew Howroyd, May 18 2020

Extensions

More terms from Franck Maminirina Ramaharo, Nov 30 2018
a(20) corrected by Andrew Howroyd, May 18 2020