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.

A268482 Triangle that arise in the study of Galois polynomials.

Original entry on oeis.org

1, -1, 8, 4, -76, 264, -33, 1248, -9735, 22080, 456, -32088, 440448, -2085096, 3715440, -9460, 1216600, -26297700, 205444800, -704121000, 1087450320, 274800, -64995600, 2073673920, -23974142160, 129203087760, -354403429920, 500558083200
Offset: 1

Views

Author

Michel Marcus, Feb 05 2016

Keywords

Examples

			First few rows are:
1;
-1, 8;
4, -76, 264;
-33, 1248, -9735, 22080;
456, -32088, 440448, -2085096, 3715440;
...
		

Crossrefs

Cf. A008292 (Eulerian numbers), A002190 (first column unsigned).

Programs

  • Mathematica
    c[k_] := c[k] = 1 - Sum[Binomial[k, j] Binomial[k-1, j-1] c[j], {j, k-1}];
    eul[n_, x_] := Sum[(-1)^j Binomial[n+1, j] (x-j+1)^n, {j, 0, x+1}];
    G[k_, m_] := G[k, m] = If [k==0 && m==0, 1, Sum[Binomial[k, j] Binomial[ k-1, j-1] c[j] Sum[eul[2j-1, i-1] G[k-j, m-i], {i, m}]/(2j-1)!, {j, k}]];
    Table[(2n-1)! G[n, k], {n, 7}, {k, n}] // Flatten (* Jean-François Alcover, Sep 27 2018, from PARI *)
  • PARI
    C(k) = {my(j); 1 - sum(j=1, k-1, binomial(k, j)*binomial(k-1, j-1)*C(j))};
    eul(n, x) = {my(j); sum(j=0, x+1, (-1)^j*binomial(n+1, j)*(x+1-j)^n)};
    G(k, m) = if ((k==0) && (m==0), 1, sum(j=1, k, binomial(k,j)*binomial(k-1,j-1)*C(j)*sum(i=1, m, eul(2*j-1,i-1)*G(k-j, m-i))/(2*j-1)!));
    tabl(nn) = for (n=1, nn, for (k=1, n, print1((2*n-1)!*G(n,k), ", "));print(););