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 1-3 of 3 results.

A211233 Triangle read by rows: T(n,k) is the k-th generalized Eulerian number of order n and degree 3, n >= 1.

Original entry on oeis.org

1, 2, 3, 1, 4, 10, 4, 1, 1, 7, 27, 13, -13, -27, -7, -1, 1, 12, 69, 16, -182, -376, -182, 16, 69, 12, 1, 1, 21, 176, -88, -1375, -3123, -1608, 1608, 3123, 1375, 88, -176, -21, -1, 1, 38, 456, -886, -8292, -20322, -6536, 35890, 65862, 35890, -6536, -20322, -8292, -886, 456, 38, 1
Offset: 1

Views

Author

N. J. A. Sloane, Apr 05 2012

Keywords

Examples

			Triangle begins
  1,  2,   3;
  1,  4,  10,   4,     1;
  1,  7,  27,  13,   -13,   -27,    -7,   -1;
  1, 12,  69,  16,  -182,  -376,  -182,   16,   69,   12,  1;
  1, 21, 176, -88, -1375, -3123, -1608, 1608, 3123, 1375, 88, ... ;
  ...
		

Crossrefs

Row sums of even rows are A047682; row sums of odd rows are zero for n > 1.

Programs

  • PARI
    T(n,r=3)={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

From Andrew Howroyd, May 18 2020: (Start)
T(n,k) = k*T(n-1,k) - (n-k)*T(n-1,k-1) - (2*n-k)*T(n-1,k-2) - (3*n-k)*T(n-1,k-3) for n > 1.
A047682(n) = Sum_{k>=1} T(2*n, k).
(End)

Extensions

Terms a(39) and beyond from Andrew Howroyd, May 18 2020

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

A211235 Array of generalized Eulerian numbers C(n,k) read by antidiagonals.

Original entry on oeis.org

1, 1, 2, 1, 4, 3, 1, 7, 10, 4, 1, 12, 27, 20, 5, 1, 21, 69, 77, 35, 6, 1, 38, 176, 272, 182, 56, 7, 1, 71, 456, 936, 846, 378, 84, 8, 1, 136, 1205, 3210, 3750, 2232, 714, 120, 9, 1, 265, 3247, 11075, 16290, 12342, 5214, 1254, 165, 10
Offset: 1

Views

Author

N. J. A. Sloane, Apr 05 2012

Keywords

Examples

			Array begins:
  1,       2,   3,   4,    5,     6, ... A000027
  1,       4,  10,  20,   35,    56, ... A000292
  1,       7,  27,  77,  182,   378, ... A005585
  1,      12,  69, 272,  846,  2232, ... A101097
  1,      21, 176, 936, 3750, 12342, ... A254681
     A005126,
  ...
Triangle begins:
  1
  1  2
  1  4   3
  1  7  10   4
  1 12  27  20   5
  1 21  69  77  35  6
  1 38 176 272 182 56 7
  ...
		

Crossrefs

Programs

  • Maple
    A211235 := (n, k) -> add(binomial(n-i, k-i)*i^(n-k), i = 1 .. k): for n from 1 to 10 do seq(A211235(n, k), k = 1 .. n) end do; # Peter Bala, Oct 27 2015
  • Mathematica
    T[n_, k_] := Sum[Binomial[n-i, k-i] * i^(n-k), {i, 1, k}]; Table[T[n, k], {n,1,10}, {k,1,n}] //Flatten (* Amiram Eldar, Nov 30 2018 *)

Formula

From Peter Bala, Oct 27 2015: (Start)
O.g.f. of n-th row of square array: 1/(1 - x)^n * (x*d/dx)^n log(1/(1 - x)), for n >= 1.
E.g.f. of square array: log((1 - x)/(1 - x*exp(t/(1 - x)))).
Read as a triangle: T(n,k) = Sum_{i = 1..k} binomial(n-i,k-i)*i^(n-k) for 1 <= k <= n.
n-th row polynomial of triangle: Sum_{i = 0..n-1} x^i*(x + i)^(n-i). (End)

Extensions

Terms a(37)-a(55) added by Peter Bala, Oct 27 2015
Showing 1-3 of 3 results.