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.

A272098 Triangle read by rows, T(n,k) = Sum_{j=0..n} (-1)^(n-j)*C(-j-1,-n-1)*E1(j,k), E1 the Eulerian numbers A173018, for n >= 0 and 0 <= k <= n.

Original entry on oeis.org

1, 2, 0, 4, 1, 0, 8, 7, 1, 0, 16, 33, 15, 1, 0, 32, 131, 131, 31, 1, 0, 64, 473, 883, 473, 63, 1, 0, 128, 1611, 5111, 5111, 1611, 127, 1, 0, 256, 5281, 26799, 44929, 26799, 5281, 255, 1, 0, 512, 16867, 131275, 344551, 344551, 131275, 16867, 511, 1, 0
Offset: 0

Views

Author

Peter Luschny, Apr 20 2016

Keywords

Examples

			Triangle starts:
  [1]
  [2, 0]
  [4, 1, 0]
  [8, 7, 1, 0]
  [16, 33, 15, 1, 0]
  [32, 131, 131, 31, 1, 0]
  [64, 473, 883, 473, 63, 1, 0]
  [128, 1611, 5111, 5111, 1611, 127, 1, 0]
		

Crossrefs

Cf. A000522 (row sums), A000079 (col. 0), A066810 (col. 1).
Cf. A173018.

Programs

  • Maple
    T := (n, k) -> add((-1)^(n-j)*combinat:-eulerian1(j,k)*binomial(-j-1,-n-1), j=0..n): seq(seq(T(n, k), k=0..n), n=0..10);
    # Or:
    egf := (exp(x)*(y - 1))/(y - exp(x*(y - 1))); ser := series(egf, x, 12):
    cx := n -> series(coeff(ser, x, n), y, n + 2):
    seq(seq(n!*coeff(cx(n), y, k), k = 0..n), n = 0..9); # Peter Luschny, Aug 14 2022
  • Mathematica
    <Emanuele Munarini, Oct 19 2023 *)

Formula

E.g.f.: (exp(x)*(y - 1))/(y - exp(x*(y - 1))). - Peter Luschny, Aug 14 2022
T(n,k) = Sum_{i=0..n} Binomial(n,i)*Eulerian(i,k), where Eulerian(n,k) = Eulerian numbers A173018. Equivalently, if T is the matrix generated by T(n,k), B is the binomial matrix and E is the Eulerian matrix, then T = B E. - Emanuele Munarini, Oct 19 2023