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.

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A158616 Table of expansion coefficients [x^m] of the Rayleigh polynomial of index 2n.

Original entry on oeis.org

1, 1, 2, 11, 5, 38, 14, 946, 1026, 362, 42, 4580, 4324, 1316, 132, 202738, 311387, 185430, 53752, 7640, 429, 3786092, 6425694, 4434158, 1596148, 317136, 33134, 1430, 261868876, 579783114, 547167306, 287834558, 92481350, 18631334, 2305702
Offset: 1

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Author

R. J. Mathar, Mar 22 2009

Keywords

Examples

			The polynomials of low index are Phi(2,x)=Phi(4,x) = 1 ; Phi(6,x)=2 ; Phi(8,x)=11+5x ; Phi(10,x)=38+14x ; Phi(12,x)=946+1026x+362x^2+42x^3 ;
Triangle begins:
  1,
  1,
  2,
  11,5,
  38,14,
  946,1026,362,42,
  4580,4324,1316,132,
  202738,311387,185430,53752,7640,429,
  ...
		

Crossrefs

Cf. A000992, A000175 (first column), A000331 (2nd column).

Programs

  • Maple
    sig2n := proc(n,nu) option remember ; if n = 1 then 1/4/(nu+1) ; else add( procname(k,nu)*procname(n-k,nu),k=1..n-1)/(nu+n) ; simplify(%) ; fi; end:
    Phi2n := proc(n,nu) local k ; 4^n*mul( (nu+k)^(floor(n/k)),k=1..n)*sig2n(n,nu) ; factor(%) ; end:
    for n from 1 to 14 do rpoly := Phi2n(n,nu) ; print(coeffs(rpoly)) ; od:
  • Mathematica
    sig2n[n_, nu_] := sig2n[n, nu] = If[n == 1, 1/4/(nu + 1), Sum[sig2n[k, nu]*sig2n[n - k, nu], {k, 1, n - 1}]/(nu + n)] // Simplify;
    Phi2n[n_, nu_] := 4^n*Product[(nu + k)^Floor[n/k], {k, 1, n}]*sig2n[n, nu];
    T[n_] := CoefficientList[Phi2n[n, x], x];
    Table[T[n], {n, 1, 14}] // Flatten (* Jean-François Alcover, Dec 01 2023, after R. J. Mathar *)

A000331 Related to zeros of Bessel function.

Original entry on oeis.org

5, 14, 1026, 4324, 311387, 6425694, 579783114, 4028104212, 7315072725560, 61358264615344, 9569450876916944, 1632353370882506848, 1365475358484643531856, 15211641461623992544160, 74766806258361827981250240, 936580261005146914634459520, 6083678228249789825160175706880, 1936651082361926268672618636234240, 688115696843061332335070140230720000, 10517068622936239459488783307672335360, 2913914903970372007778735454555848514846720
Offset: 4

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Author

Keywords

Comments

a(n) is coefficient of nu in Rayleigh polynomial of index 2n.

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A158616.

Programs

  • Mathematica
    sig2n[n_, nu_] := sig2n[n, nu] = If[n == 1, 1/4/(nu + 1), Sum[sig2n[k, nu]*sig2n[n - k, nu], {k, 1, n - 1}]/(nu + n)] // Simplify;
    Phi2n[n_, nu_] := 4^n*Product[(nu + k)^Floor[n/k], {k, 1, n}]*sig2n[n, nu];
    a[n_] := Coefficient[Phi2n[n, x], x, 1];
    Table[a[n], {n, 4, 24}] (* Jean-François Alcover, Dec 01 2023, after R. J. Mathar in A158616 *)

Extensions

More terms from Sean A. Irvine, Nov 11 2010
Showing 1-2 of 2 results.