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.

A223524 Triangle S(n, k) by rows: coefficients of 2^(n/2)*(x^(1/2)*d/dx)^n, where n =0, 2, 4, 6, ...

Original entry on oeis.org

1, 1, 2, 3, 12, 4, 15, 90, 60, 8, 105, 840, 840, 224, 16, 945, 9450, 12600, 5040, 720, 32, 10395, 124740, 207900, 110880, 23760, 2112, 64, 135135, 1891890, 3783780, 2522520, 720720, 96096, 5824, 128, 2027025, 32432400
Offset: 1

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Author

Udita Katugampola, Mar 21 2013

Keywords

Comments

Triangle by rows of the coefficients of 2^n * n! *|L(n,-1/2,x)|, with L the generalized Laguerre polynomials. - Ali Pourzand, Mar 28 2025

Examples

			Triangle begins:
  1;
  1, 2;
  3, 12, 4;
  15, 90, 60, 8;
  105, 840, 840, 224, 16;
  945, 9450, 12600, 5040, 720, 32;
  10395, 124740, 207900, 110880, 23760, 2112, 64;
  ...
Expansion takes the form:
  2^1 (x^(1/2)*d/dx)^2 = 1*d/dx + 2*x*d^2/dx^2.
  2^2 (x^(1/2)*d/dx)^4 = 3*d^2/dx^2 + 12*x*d^3/dx^3 + 4*x^2*d^4/dx^4.
		

Crossrefs

Rows includes even rows of A223168.

Programs

  • Maple
    a[0]:= f(x):
    for i from 1 to 20 do
    a[i]:= simplify(2^((i+1)mod 2)*x^(1/2)*(diff(a[i-1],x$1)));
    end do:
    for j from 1 to 10 do
    b[j]:=a[2j];
    end do;
  • Mathematica
    Flatten[Abs[Table[CoefficientList[2^n n! LaguerreL[n, -1/2, x], x], {n, 0, 7}]]] (* Ali Pourzand, Mar 28 2025 *)