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.

A223523 Triangle S(n, k) by rows: coefficients of 2^((n-1)/2)*(x^(1/2)*d/dx)^n, where n = 1, 3, 5, ...

Original entry on oeis.org

1, 3, 2, 15, 20, 4, 105, 210, 84, 8, 945, 2520, 1512, 288, 16, 10395, 34650, 27720, 7920, 880, 32, 135135, 540540, 540540, 205920, 34320, 2496, 64, 2027025, 9459450, 11351340, 5405400, 1201200, 131040, 6720, 128
Offset: 1

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Author

Udita Katugampola, Mar 21 2013

Keywords

Comments

Triangle S(n,n-k) by rows: coefficients of 2^n * |L(n,1/2,x)|, with L the generalized Laguerre polynomials.

Examples

			Triangle begins:
1;
3, 2;
15, 20, 4;
105, 210, 84, 8;
945, 2520, 1512, 288, 16;
10395, 34650, 27720, 7920, 880, 32;
135135, 540540, 540540, 205920, 34320, 2496, 64;
.
.
Expansion takes the form:
2^0 (x^(1/2)*d/dx)^1 = 1*x^(1/2)*d/dx.
2^1 (x^(1/2)*d/dx)^3 = 3*x^(1/2)*d^2/dx^2 + 2*x^(3/2)*d^3/dx^3.
2^2 (x^(1/2)*d/dx)^5 = 15*x^(1/2)*d^3/dx^3 + 20*x^(3/2)*d^4/dx^4 + 4*x^(5/2)*d^5/dx^5.
		

Crossrefs

Rows includes odd rows of A223168.
Rows includes absolute values of A098503 from right to left of the triangular form.

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-1];
    end do;

Formula

T(n, k) = 2^n * n!/(n-k)! * C(n+1/2, k), n>=0, k<=n.