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 1-3 of 3 results.

A129891 Sum of coefficients of polynomials defined in comments lines.

Original entry on oeis.org

1, 2, 4, 9, 20, 44, 96, 209, 455, 991, 2159, 4704, 10249, 22330, 48651, 105997, 230938, 503150, 1096225, 2388372, 5203604, 11337218, 24700671, 53815949, 117250109, 255455647, 556567394, 1212606837, 2641935832, 5756049469, 12540844137
Offset: 0

Views

Author

Paul Curtz, Jun 04 2007

Keywords

Comments

At the same time that I introduced the polynomials P(n,x) defined by P(0,x)=1 and for n>0, P(n,x) = (-1)^n/(n+1) + x*Sum_{ i=0..n-1 } ( (-1)^i/(i+1) )*P(n-1-i,x) (Gazette des Mathematiciens 1992), I gave the generalization P(0,x) = u(0), P(n,x) = u(n) + x*Sum_{ i=0..n-1 } u(i)*P(n-1-i,x).
For u(n), n>=0, = 1 1 1 2 3 4 5 6 7 8 ... the array of coefficients of the polynomials P(n,x) is:
1
1 1
1 2 1
2 3 3 1
3 6 6 4 1
4 11 13 10 5 1
5 18 27 24 15 6 1
6 28 51 55 40 21 7 1
whose row sums are the present sequence.
The alternating row sums are 1 0 0 1 0 0 0 -1 ...
The antidiagonal sums are 1 1 2 4 7 13 23 41 73 ...
The first column of the inverse matrix is 1 -1 1 -2 5 -11 25 -63 ...

References

  • Paul Curtz, Gazette des Mathématiciens, 1992, no. 52, p. 44.

Crossrefs

Sums of coefficients of polynomials defined in A140530.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1-x+x^3)/(1-3*x+2*x^2-x^4) )); // G. C. Greubel, Oct 24 2023
    
  • Maple
    a:= n-> (Matrix([1, 1, 0, 1]). Matrix(4, (i, j)-> if i=j-1 then 1 elif j=1 then [3, -2, 0, 1][i] else 0 fi)^n)[1, 1]:
    seq(a(n), n=0..50);  # Alois P. Heinz, Oct 14 2009
  • Mathematica
    u[n_ /; n < 3] = 1; u[n_] := n-1;
    p[0][x_] := u[0]; p[n_][x_] := p[n][x] = u[n] + x*Sum[ u[i]*p[n-i-1][x] , {i, 0, n-1}] // Expand;
    row[n_] := CoefficientList[ p[n][x], x];
    Table[row[n] // Total, {n, 0, 30}] (* Jean-François Alcover, Oct 02 2012 *)
  • SageMath
    def A129891_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1-x+x^3)/(1-3*x+2*x^2-x^4) ).list()
    A129891_list(40) # G. C. Greubel, Oct 24 2023

Formula

G.f.: (1-x+x^3)/(1-3*x+2*x^2-x^4). - Alois P. Heinz, Oct 14 2009

Extensions

Edited by N. J. A. Sloane, Jul 05 2007
More terms from Alois P. Heinz, Oct 14 2009

A141411 Defined in comments.

Original entry on oeis.org

3, 1, 31, 28, 365, 514, 4388, 8220, 53871, 122284, 673222, 1748055, 8535397, 24383499, 109449848, 334783855, 1415768769, 4548229589, 18434398665, 61345927764, 241210652738, 823296868656, 3167642169823, 11010462627756, 41708741708554, 146886286090602
Offset: 0

Views

Author

Paul Curtz, Jun 18 2007

Keywords

Comments

Given any sequence {u(i), i >= 0} we define a family of polynomials by P(0,x) = u(0), P(n,x) = u(n) + x*Sum_{i=0..n-1} u(i)*P(n-i-1, x). Then we set a(n) = (P(n,-1)+P(n,1))/2.
For the present example we take {u(i)} to be 3,1,4,1,5,9,... (A000796).

References

  • P. Curtz, Gazette des Mathematiciens, 1992, 52, p.44.
  • P. Flajolet, X. Gourdon and B. Salvy, Gazette des Mathematiciens, 1993, 55, pp.67-78 .

Crossrefs

See A130620 for another version.

Programs

  • Maple
    u:= proc(n) Digits:= max(n+10);
           trunc (10* frac(evalf(Pi*10^(n-1))))
        end:
    P:= proc(n) option remember; local i, x;
          if n=0 then u(0)
        else unapply(expand(u(n)+x*add(u(i)*P(n-i-1)(x), i=0..n-1)), x)
          fi
        end:
    a:= n-> (P(n)(1)+P(n)(-1))/2:
    seq(a(n), n=0..30);  # Alois P. Heinz, Sep 06 2009
  • Mathematica
    nmax = 25; digits = RealDigits[Pi, 10, nmax+1][[1]]; p[0][] = digits[[1]]; p[n][x_] := p[n][x] = digits[[n+1]] + x*Sum[digits[[i+1]] p[n-i-1][x], {i, 0, n-1}]; a[n_] := (p[n][1] + p[n][-1])/2; Table[a[n], {n, 0, nmax}] (* Jean-François Alcover, Nov 22 2012 *)

Formula

a(n) ~ c * d^n, where d = 3.6412947999106071671946396356753..., c = 1.387705266307957334035092183546... . - Vaclav Kotesovec, Sep 10 2014

Extensions

Edited by N. J. A. Sloane, Aug 26 2009
Corrected and extended by Alois P. Heinz, Sep 06 2009

A100597 Based on the first matrix inverse of transformed Bernoulli numbers as defined in the Comments line.

Original entry on oeis.org

1, 1, 2, 5, 14, 49, 258, 1385, 1342, -13739, 1727362, 20549165, -892047378, -13084315271, 979519187138, 16158974238545, -1747908612654946, -32246548780758179, 4903305033480792642, 100032668564662494485, -20685044415403212103730, -462550882810484735564351
Offset: 1

Views

Author

Paul Curtz, Jun 06 2007

Keywords

Comments

A family of polynomials is defined by P(0,x) = u(0), P(n,x) = u(n) +x*Sum_{i=0..n-1} u(i)*P(n-i-1,x), where u(n) is the n-th Bernoulli number. The coefficients of P(n-1,x) are used to fill the n-th row of the infinite lower triangle matrix M. Then a(n) is given by M^(-1)[n,1] * n!.

Examples

			a(3) = 2, because M = [1; -1/2 1; 1/6 -1 1; ...], M^(-1) = [1; 1/2 1; 1/3 1 1; ...], and (1/3)*3! = 2.
		

References

  • P. Curtz, Gazette des Mathematiciens, 1992, 52, p.44.
  • P. Flajolet, X. Gourdon and B. Salvy, Gazette des Mathematiciens, 1993, 55, pp.67-78.

Crossrefs

Programs

  • Maple
    P:= proc(n) option remember; local i, u, x; u:= bernoulli; `if`(n=0, u(0), unapply(expand(u(n) +x *add(u(i) *P(n-i-1)(x), i=0..n-1)), x)) end: a:= n-> (1/Matrix(n, (i, j)-> coeff(P(i-1)(x), x, j-1)))[n, 1] *n!: seq(a(n), n=1..30);  # Alois P. Heinz, Oct 12 2009
  • Mathematica
    p[0, x_] = BernoulliB[0]; p[n_, x_] := p[n, x] = BernoulliB[n] + x*Sum[BernoulliB[i]*p[n-i-1, x], {i, 0, n-1}]; t[m_] := Table[ PadRight[CoefficientList[p[n, x], x], m+1], {n, 0, m}]; mmax = 20; Inverse[t[mmax-1]][[All, 1]]*Range[mmax]!
    (* Jean-François Alcover, Jun 29 2011 *)

Extensions

Edited and more terms from Alois P. Heinz, Oct 12 2009
Showing 1-3 of 3 results.