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.

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

Views

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

A241066 Array t(n,k) = k^(2n)*(k^(2n)-1)*BernoulliB(2n)/(2n), n>=1, k>=2, absolute values read by ascending antidiagonals.

Original entry on oeis.org

1, 2, 6, 16, 54, 20, 272, 2106, 544, 50, 7936, 179334, 66560, 3250, 105, 353792, 26414586, 17895424, 968750, 13986, 196, 22368256, 5957217414, 8329625600, 635781250, 8637840, 48020, 336, 1903757312, 1906398972666, 5937093935104, 722480468750, 11754617616, 54925276, 139776, 540
Offset: 1

Views

Author

Jean-François Alcover, Apr 16 2014

Keywords

Comments

For any integers n and k, the ratio k^(2n)*(k^(2n)-1)*B(2n)/(2n) is always an integer.
Row 1 is A002415 = 4-D pyramidal numbers,
Row 2 and following rows are not in the OEIS,
Column 1 is A000182 = Tangent numbers,
Column 2 is A047681,
Column 3 is A047682,
Column 4 is A047683,
Column 5 and following columns are not in the OEIS.

Examples

			Array begins:
   1,        6,         20,           50,            105, ...
   2,       54,        544,         3250,          13986, ...
  16,     2106,      66560,       968750,        8637840, ...
272,   179334,   17895424,    635781250,    11754617616, ...
7936, 26414586, 8329625600, 722480468750, 27698169542400, ...
etc.
		

Crossrefs

Programs

  • Mathematica
    nmax = 8; t[n_, k_] := k^(2*n)*(k^(2*n)-1)*BernoulliB[2*n]/(2*n); Table[t[n-k+2, k] // Abs, {n, 1, nmax}, {k, 2, n+1}] // Flatten
Showing 1-2 of 2 results.