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 1-4 of 4 results.

A076256 Coefficients of the polynomials in the numerator of 1/(1+x^2) and its successive derivatives, starting with the constant term.

Original entry on oeis.org

1, 0, -2, -2, 0, 6, 0, 24, 0, -24, 24, 0, -240, 0, 120, 0, -720, 0, 2400, 0, -720, -720, 0, 15120, 0, -25200, 0, 5040, 0, 40320, 0, -282240, 0, 282240, 0, -40320, 40320, 0, -1451520, 0, 5080320, 0, -3386880, 0, 362880, 0, -3628800, 0, 43545600, 0, -91445760, 0, 43545600, 0, -3628800
Offset: 0

Views

Author

Mohammad K. Azarian, Nov 05 2002

Keywords

Comments

Let T(n, k) be the coefficient of x^k in the numerator of the n-th derivative of 1/(1+x^2).
The denominators are (1+x^2)^(n+1), whose coefficients are the binomial coefficients, A007318.

Examples

			Triangle begins:
     1;
     0,    -2;
    -2,     0,     6;
     0,    24,     0,     -24;
    24,     0,  -240,       0,    120;
     0,  -720,     0,    2400,      0,   -720;
  -720,     0, 15120,       0, -25200,      0, 5040;
     0, 40320,     0, -282240,      0, 282240,    0, -40320;
   ...
		

Crossrefs

Programs

  • Mathematica
    a[n_, k_] := Coefficient[Expand[Together[(1+x^2)^(n+1)*D[1/(1+x^2), {x, n}]]], x, k]; Flatten[Table[a[n, k], {n, 0, 10}, {k, 0, n}]]
  • PARI
    T(n,k) = if((n+k)%2, 0, (-1)^((n+k)/2)*n!*binomial(n+1, k)) \\ Andrew Howroyd, Aug 08 2024

Formula

T(n, k) = (-1)^((n+k)/2)*n!*binomial(n+1, k) for n + k even;
T(n, k) = 0 for n + k odd.
E.g.f.: A(x,t) = Sum_{n>=0} Sum_{k=0..n} T(n,k)*x^n*t^k/n! = 1/(1 + 2*x*t + x^2*(1+t^2)). - Fabian Pereyra, Aug 08 2024
From Fabian Pereyra, Sep 11 2024: (Start)
T(n,k) = -n*(n-1)*T(n-2,k) - 2*n*T(n-1,k-1) - n*(n-1)*T(n-2,k-2), with T(0,0) = 1, T(n,k) = 0 if k<0 or k>n.
Let p(n,x) the n-th polynomial in x defined by: p(n,x) = Sum_{k=0..n} T(n,k)*x^k.
Then, the p(n,x) satisfy:
p(n,x) = -2*n*x*p(n-1,x) - n*(n-1)*(1+x^2)*p(n-2,x).
p'(n,x) = -n*(n+1)*p(n-1,x).
(1+x^2)*p''(n,x) - 2*n*x*p'(n,x) + n*(n+1)*p(n,x) = 0.
Integral_{x=-inf..inf} p(n,x)*p(m,x)*(1/(1+x^2))^(max(n,m)+1) dx = n!*(n+1)!*pi* delta(n,m), where delta(n,m) is the Kronecker delta. (End)
Sum_{k=0..n} abs(T(n,k)) = A000165(n). - Alois P. Heinz, Sep 18 2024

Extensions

Edited by Dean Hickerson, Nov 28 2002

A076257 Coefficients of the polynomials in the numerator of 1/(1+x^2) and its successive derivatives, starting with the coefficient of the highest power of x.

Original entry on oeis.org

1, -2, 0, 6, 0, -2, -24, 0, 24, 0, 120, 0, -240, 0, 24, -720, 0, 2400, 0, -720, 0, 5040, 0, -25200, 0, 15120, 0, -720, -40320, 0, 282240, 0, -282240, 0, 40320, 0, 362880, 0, -3386880, 0, 5080320, 0, -1451520, 0, 40320, -3628800, 0, 43545600, 0, -91445760, 0, 43545600, 0
Offset: 0

Views

Author

Mohammad K. Azarian, Nov 05 2002

Keywords

Comments

Denominator of n-th derivative is (1+x^2)^(n+1), whose coefficients are the binomial coefficients, A007318.

Examples

			The coefficients of the numerators starting with the coefficient of the highest power of x are 1; -2,0; 6,0,-2; -24,0,24,0; ...
		

Crossrefs

Programs

  • Mathematica
    a[n_, k_] := Coefficient[Expand[Together[(1+x^2)^(n+1)*D[1/(1+x^2), {x, n}]]], x, k]; Flatten[Table[a[n, k], {n, 0, 10}, {k, n, 0, -1}]]

Formula

For 0<=k<=n, let a(n, k) be the coefficient of x^k in the numerator of the n-th derivative of 1/(1+x^2). If n+k is even, a(n, k) = (-1)^((n+k)/2)*n!*binomial(n+1, k); if n+k is odd, a(n, k)=0.

Extensions

Edited by Dean Hickerson, Nov 28 2002

A076741 Nonzero coefficients of the polynomials in the numerator of 1/(1+x^2) and its successive derivatives, starting with the constant term.

Original entry on oeis.org

1, -2, -2, 6, 24, -24, 24, -240, 120, -720, 2400, -720, -720, 15120, -25200, 5040, 40320, -282240, 282240, -40320, 40320, -1451520, 5080320, -3386880, 362880, -3628800, 43545600, -91445760, 43545600, -3628800, -3628800, 199584000, -1197504000
Offset: 0

Views

Author

Mohammad K. Azarian, Nov 11 2002

Keywords

Comments

Denominator of n-th derivative is (1+x^2)^(n+1), whose coefficients are the binomial coefficients, A007318.

Examples

			The nonzero coefficients of the numerators starting with the constant term are: 1; -2; -2,6; 24,-24; ...
		

References

  • Roland Zumkeller, Formal global optimization with Taylor models, IJCAR (Ulrich Furbach and Natara jan Shankar, eds.), Lecture Notes in Computer Science, vol. 4130, Springer, 2006, pp. 408-422.

Crossrefs

Programs

  • Mathematica
    a[n_, k_] := Coefficient[Expand[Together[(1+x^2)^(n+1)*D[1/(1+x^2), {x, n}]]], x, k]; Select[Flatten[Table[a[n, k], {n, 0, 10}, {k, 0, n}]], #!=0&]

Formula

For 0<=k<=n, let a(n, k) be the coefficient of x^k in the numerator of the n-th derivative of 1/(1+x^2). If n+k is even, a(n, k) = (-1)^((n+k)/2)*n!*binomial(n+1, k); if n+k is odd, a(n, k)=0.

Extensions

Edited by Dean Hickerson, Nov 28 2002

A131980 A coefficient tree from the list partition transform relating A000129, A000142, A000165, A110327, and A110330.

Original entry on oeis.org

1, 2, 6, 2, 24, 24, 120, 240, 24, 720, 2400, 720, 5040, 25200, 15120, 720, 40320, 282240, 282240, 40320, 362880, 3386880, 5080320, 1451520, 40320, 3628800, 43545600, 91445760, 43545600, 3628800, 39916800, 598752000, 1676505600, 1197504000, 199584000, 3628800
Offset: 0

Views

Author

Tom Copeland, Oct 30 2007, Nov 29 2007, Nov 30 2007

Keywords

Comments

Construct the infinite array of polynomials
a(0,t) = 1
a(1,t) = 2
a(2,t) = 6 + 2 t
a(3,t) = 24 + 24 t
a(4,t) = 120 + 240 t + 24 t^2
a(5,t) = 720 + 2400 t + 720 t^2
a(6,t) = 5040 + 25200 t + 15120 t^2 + 720 t^3
This array is the reciprocal array of the following array b(n,t) under the list partition transform and its associated operations described in A133314.
b(0,t) = 1, b(1,t) = -2, b(2,t) = -2*(t-1), b(n,t) = 0 for n>2.
Then A000165(n) = a(n,1).
Lower triangular matrix A110327 = binomial(n,k)*a(n-k,2).
n! * A000129(n+1) = a(n,2) = A110327(n,0).
A110330 = matrix inverse of binomial(n,k)*a(n-k,2) = binomial(n,k)*b(n-k,2).
A000142(n+1) = a(n,0).
From Peter Bala, Sep 09 2013: (Start)
Let {P(n,x)}n>=0 be a polynomial sequence. Koutras has defined generalized Eulerian numbers associated with the sequence P(n,x) as the coefficients A(n,k) in the expansion of P(n,x) in a series of factorials of degree n, namely P(n,x) = Sum_{k=0..n} A(n,k)* binomial(x+n-k,n). The choice P(n,x) = x^n produces the classical Eulerian numbers of A008292. Let now P(n,x) = x*(x + 1)*...*(x + n - 1) denote the n-th rising factorial polynomial. Then the present table is the generalized Eulerian numbers associated with the polynomial sequence P(n,2*x). See A228955 for the generalized Eulerian numbers associated with the polynomial sequence P(n,2*x + 1). (End)

Examples

			Triangle begins as:
        1;
        2;
        6,        2;
       24,       24;
      120,      240,       24;
      720,     2400,      720;
     5040,    25200,    15120,      720;
    40320,   282240,   282240,    40320;
   362880,  3386880,  5080320,  1451520,   40320;
  3628800, 43545600, 91445760, 43545600, 3628800;
		

Crossrefs

Cf. A228955.

Programs

  • GAP
    Flat(List([0..10], n-> List([0..Int(n/2)], k-> Factorial(n)*Binomial(n+1, 2*k+1) ))); # G. C. Greubel, Dec 30 2019
  • Magma
    [Factorial(n)*Binomial(n+1, 2*k+1): k in [0..Floor(n/2)], n in [0..10]]; // G. C. Greubel, Dec 30 2019
    
  • Maple
    for n from 0 to 10 do
    seq( n!*binomial(n+1,2*k+1), k = 0..floor(n/2) )
    end do; # Peter Bala, Sep 09 2013
  • Mathematica
    Table[n!*Binomial[n+1, 2*k+1], {n,0,10}, {k,0,Floor[n/2]}]//Flatten (* G. C. Greubel, Dec 30 2019 *)
  • PARI
    T(n,k) = n!*binomial(n+1, 2*k+1);
    for(n=0,10, for(k=0, n\2, print1(T(n,k), ", "))) \\ G. C. Greubel, Dec 30 2019
    
  • Sage
    [[factorial(n)*binomial(n+1, 2*k+1) for k in (0..floor(n/2))] for n in (0..10)] # G. C. Greubel, Dec 30 2019
    

Formula

E.g.f. for the polynomials b(.,t), introduced above, is 1 - 2x - (t-1) * x^2; therefore e.g.f. for the polynomials a(.,t), which are the row polynomials of this array, is 1 / ( 1 - 2x - (t-1) * x^2 ) = (t-1) / ( t - ( 1 + x*(t-1) )^2 ).
Also, a(n,t) = (1 - t*u^2)^(n+1) (D_u)^n [ 1 / (1 - t*u^2) ] with eval. at u = 1/t. Compare A076743.
a(n,t) = n!*Sum_{k>=0} binomial(n+1,2k+1) * t^k = n!*Sum_{k>=0} A034867(n,k) * t^k.
Additional relations are given by formulas in A133314.
From Peter Bala, Sep 09 2013: (Start)
Recurrence equation: T(n+1,k) = (n+2 +2*k)T(n,k) + (n +2 -2*k)T(n,k-1).
Let P(n,x) = x*(x + 1)*...*(x + n - 1) denote the n-th rising factorial.
T(n,k) = Sum_{j=0..k+1} (-1)^(k+1-j)*binomial(n+1,k+1-j)*P(n,2*j) for n >= 1.
The row polynomial a(n,t) satisfies t*a(n,t)/(1 - t)^(n+1) = Sum_{j>=1} P(n,2*j)*t^j. For example, for n = 3 we have t*(24 + 24*t)/(1 - t)^4 = 2*3*4*t + (4*5*6)*t^2 + (6*7*8)*t^3 + ..., while for n = 4 we have t*(120 + 240*t + 24*t^2)/(1 - t)^5 = (2*3*4*5)*t + (4*5*6*7)*t^2 + (6*7*8*9)*t^3 + .... (End)

Extensions

Removed erroneous and duplicate statements. - Tom Copeland, Dec 03 2013
Showing 1-4 of 4 results.