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.

A099212 a(n) = -2*a(n-1) + 4*a(n-3), with a(0) = 1, a(1) = a(2) = 0.

Original entry on oeis.org

1, 0, 0, 4, -8, 16, -16, 0, 64, -192, 384, -512, 256, 1024, -4096, 9216, -14336, 12288, 12288, -81920, 212992, -376832, 425984, 0, -1507328, 4718592, -9437184, 12845056, -6815744, -24117248, 99614720, -226492416, 356515840, -314572800, -276824064, 1979711488
Offset: 0

Views

Author

Paul Barry, Oct 06 2004

Keywords

Comments

Binomial transform is A099213.

Crossrefs

Cf. A099211.

Programs

  • Mathematica
    LinearRecurrence[{-2,0,4},{1,0,0},40] (* Harvey P. Dale, May 02 2019 *)

Formula

G.f.: (1 + 2*x)/(1 + 2*x - 4*x^3).

Extensions

a(31) onwards from Andrew Howroyd, Mar 19 2025

A099214 a(n)=4a(n-1)-4a(n-2)+4a(n-3).

Original entry on oeis.org

1, 2, 4, 12, 40, 128, 400, 1248, 3904, 12224, 38272, 119808, 375040, 1174016, 3675136, 11504640, 36014080, 112738304, 352915456, 1104764928, 3458351104, 10826006528, 33889681408, 106088103936, 332097716224, 1039597174784
Offset: 0

Views

Author

Paul Barry, Oct 06 2004

Keywords

Comments

Binomial transform of A099213.

Crossrefs

Cf. A073724.

Formula

G.f.: (1-2x)/((1-2x)^2-4x^3); a(n)=sum{k=0..floor(n/3), binomial(n-k, 2k)4^k*2^(n-3k)}.

A123102 a(0)=1, a(1)=0, a(2)=1, a(n) = a(n-1) + a(n-2) + 3*a(n-3).

Original entry on oeis.org

1, 0, 1, 4, 5, 12, 29, 56, 121, 264, 553, 1180, 2525, 5364, 11429, 24368, 51889, 110544, 235537, 501748, 1068917, 2277276, 4851437, 10335464, 22018729, 46908504, 99933625, 212898316, 453557453, 966256644, 2058509045, 4385438048
Offset: 0

Views

Author

Philippe Deléham, Sep 27 2006

Keywords

Crossrefs

Cf. A099213.

Programs

  • Mathematica
    LinearRecurrence[{1,1,3},{1,0,1},40] (* Harvey P. Dale, May 04 2018 *)
  • PARI
    Vec((1-x)/(1-x-x^2-3*x^3) + O(x^40)) \\ Michel Marcus, Aug 07 2022

Formula

a(n) + a(n+1) = A099213(n+1).
G.f.: (1-x)/(1-x-x^2-3*x^3).
If p[1]=0, p[2]=1, p[i]=4, (i>2), and if A is Hessenberg matrix of order n defined by: A[i,j]=p[j-i+1], (i<=j), A[i,j]=-1, (i=j+1), and A[i,j]=0 otherwise, then, for n>=1, a(n)=det A. - Milan Janjic, May 02 2010

Extensions

Corrected by T. D. Noe, Nov 07 2006
Showing 1-3 of 3 results.