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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A161159 a(n) = A003739(n)/(5*A001906(n)*A006238(n)).

Original entry on oeis.org

9, 245, 7776, 254035, 8336079, 273725760, 8988999201, 295197803645, 9694285226784, 318360072624475, 10454936893196391, 343339870595441280, 11275272921720374649, 370279686003420394565, 12159975800265309667296
Offset: 1

Views

Author

R. J. Mathar, Jun 03 2009

Keywords

Comments

Proposed by R. Guy in the seqfan list, Mar 28 2009.

Programs

  • Magma
    I:=[9,245,7776,254035,8336079,273725760]; [n le 6 select I[n] else 40*Self(n-1)-248*Self(n-2)+430*Self(n-3)-248*Self(n-4)+40*Self(n-5)-Self(n-6): n in [1..16]]; // Vincenzo Librandi, Dec 19 2012
    
  • Maple
    seq(coeff(series(x*(9 -115*x +208*x^2 -115*x^3 +9*x^4)/((1-5*x+x^2)*(1-35*x+72*x^2-35*x^3+x^4)), x, n+1), x, n), n = 1..20); # G. C. Greubel, Dec 25 2019
  • Mathematica
    CoefficientList[Series[(9-115x+208x^2-115x^3+9x^4)/((1-5x+x^2)*(1-35x+72x^2- 35x^3+x^4)), {x, 0, 20}], x] (* Vincenzo Librandi, Dec 19 2012 *)
  • PARI
    my(x='x+O('x^30)); Vec(x*(9 -115*x +208*x^2 -115*x^3 +9*x^4)/((1-5*x+ x^2)*(1-35*x+72*x^2-35*x^3+x^4))) \\ G. C. Greubel, Dec 25 2019
    
  • Sage
    def A161159_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( x*(9 -115*x +208*x^2 -115*x^3 +9*x^4)/((1-5*x+x^2)*(1-35*x+72*x^2-35*x^3+x^4)) ).list()
    a=A161159_list(30); a[1:] # G. C. Greubel, Dec 25 2019

Formula

a(n) = 40*a(n-1) -248*a(n-2) +430*a(n-3) -248*a(n-4) +40*a(n-5) -a(n-6).
G.f.: x*(9 -115*x +208*x^2 -115*x^3 +9*x^4)/((1-5*x+x^2)*(1-35*x+72*x^2-35*x^3 +x^4)).

A161495 Expansion of x*(3*x-1)*(x-3)/(1-15*x+32*x^2-15*x^3+x^4).

Original entry on oeis.org

3, 35, 432, 5405, 67773, 850080, 10663107, 133755235, 1677792528, 21045816925, 263993558397, 3311470367040, 41538271098243, 521045872287395, 6535871471114352, 81984366749625245, 1028391763981932093
Offset: 1

Views

Author

R. J. Mathar, Jun 11 2009

Keywords

Comments

Proposed by R. Guy in the seqfan list, Mar 29 2009.

Programs

  • Mathematica
    Rest[CoefficientList[Series[x(3x-1)(x-3)/(1-15x+32x^2-15x^3+x^4), {x,0,30}], x]] (* or *) LinearRecurrence[{15,-32,15,-1},{3,35,432,5405},30] (* Harvey P. Dale, Nov 03 2011 *)

Formula

G.f. x*(3*x-1)*(x-3)/(1-15*x+32*x^2-15*x^3+x^4).
a(n) = 15*a(n-1)-32*a(n-2)+15*a(n-3)-a(n-4).
(a(n))^2 = A161159(n)*A004254(n) = A003739(n)/(5*(A001906(n))^2).
Showing 1-2 of 2 results.