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.

A007829 From random walks on complete directed triangle.

Original entry on oeis.org

0, 0, 0, 0, 0, 6, 8, 28, 44, 100, 162, 318, 514, 942, 1518, 2672, 4302, 7380, 11882, 20040, 32276, 53810, 86710, 143396, 231204, 380152, 613286, 1004188, 1620864, 2645928, 4272744, 6959326, 11242518, 18281222, 29542078, 47978666, 77552928, 125836374, 203445784
Offset: 0

Views

Author

Eric Bussian [ ebussian(AT)math.gatech.edu ]

Keywords

Crossrefs

Programs

  • Maple
    m:=35; S:=series(2*x^5*(3-2*x-3*x^2)/((1-x)*(1-x-x^2)*(1-2*x^2)*(1-x^2-x^3)), x, m+1): seq(coeff(S, x, j), j=0..m); # G. C. Greubel, Mar 11 2020
  • Mathematica
    b[n_]:= b[n]= If[n==0, 1, If[n<3, 0, b[n-2] +b[n-3]]]; Table[2*(2 +Fibonacci[n+2] -2^Floor[n/2] -p[n+7] -p[n+5]), {n,0,35}] (* G. C. Greubel, Mar 11 2020 *)
  • Sage
    def A007829_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 2*x^5*(3-2*x-3*x^2)/((1-x)*(1-x-x^2)*(1-2*x^2)*(1-x^2-x^3)) ).list()
    A007829_list(35) # G. C. Greubel, Mar 11 2020

Formula

From Colin Barker, Feb 03 2018: (Start)
G.f.: 2*x^5*(3 - 2*x - 3*x^2) / ((1 - x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - x^2 - x^3)).
a(n) = 2*a(n-1) + 3*a(n-2) - 6*a(n-3) - 4*a(n-4) + 5*a(n-5) + 5*a(n-6) - 2*a(n-7) - 2*a(n-8) for n>7.
(End)
From G. C. Greubel, Mar 11 2020: (Start)
a(n) = 2*(2 + Fibonacci(n+2) - 2^floor(n/2) - A084338(n+2)).
a(n) = 2*(2 + Fibonacci(n+2) - 2^floor(n/2) - b(n+7) - b(n+5)), where b(n) = A000931(n). (End)

A276275 Padovan like sequence: a(n) = a(n-2) + a(n-3) for n>3, a(1)=2, a(2)=2, a(3)=0.

Original entry on oeis.org

2, 2, 0, 4, 2, 4, 6, 6, 10, 12, 16, 22, 28, 38, 50, 66, 88, 116, 154, 204, 270, 358, 474, 628, 832, 1102, 1460, 1934, 2562, 3394, 4496, 5956, 7890, 10452, 13846, 18342, 24298, 32188, 42640, 56486, 74828, 99126, 131314, 173954, 230440, 305268, 404394, 535708
Offset: 1

Views

Author

Nicolas Bègue, Aug 26 2016

Keywords

Comments

Obtained from Padovan Spiral number (A134816) modulo 3 reduction periodic sequence 1112201210010, 111 112 122 220 ... fourth initialization values 220, it satisfies the same recurrence a(n) = a(n-2) + a(n-3).

Crossrefs

Programs

  • Mathematica
    RecurrenceTable[{a[n] == a[n - 2] + a[n - 3], a[1] == 2, a[2] == 2, a[3] == 0}, a, {n, 1, 48}] (* or *) CoefficientList[Series[2 x (1 + x - x^2)/(1 - x^2 - x^3), {x, 0, 47}], x] (* Michael De Vlieger, Sep 02 2016 *)
    LinearRecurrence[{0,1,1},{2,2,0},60] (* Harvey P. Dale, Jan 27 2023 *)

Formula

G.f.: 2*x*(1 + x - x^2)/(1 - x^2 - x^3).
a(n) = A134816(n) + A007307(n-3) for n>=4.
a(n) = 2*A084338(n-3) for n>=4.

A276477 a(n) = a(n-2) + a(n-3) for n >= 3, with a(0) = a(1) = 2, a(2) = 1.

Original entry on oeis.org

2, 2, 1, 4, 3, 5, 7, 8, 12, 15, 20, 27, 35, 47, 62, 82, 109, 144, 191, 253, 335, 444, 588, 779, 1032, 1367, 1811, 2399, 3178, 4210, 5577, 7388, 9787, 12965, 17175, 22752, 30140, 39927, 52892, 70067, 92819, 122959, 162886, 215778, 285845, 378664, 501623, 664509
Offset: 0

Views

Author

Nicolas Bègue, Sep 04 2016

Keywords

Comments

Padovan-like sequence linked to Perrin sequence.

Crossrefs

Programs

  • Magma
    I:=[2,2,1]; [n le 3 select I[n] else Self(n-2)+Self(n-3): n in [1..50]]; // Vincenzo Librandi, Sep 10 2016
  • Mathematica
    RecurrenceTable[{a[n] == a[n - 2] + a[n - 3], a[1] == a[2] == 2, a[3] == 1}, a, {n, 42}]
    CoefficientList[Series[(x^2 - 2 x - 2)/(x^3 + x^2 - 1), {x, 0, 41}], x] (* Michael De Vlieger, Sep 06 2016 *)
    LinearRecurrence[{0, 1, 1}, {2, 2, 1}, 60] (* Vincenzo Librandi, Sep 10 2016 *)
  • PARI
    x='x+O('x^99); Vec((x^2-2*x-2)/(x^3+x^2-1)) \\ Altug Alkan, Sep 10 2016
    

Formula

a(n) = A001608(n) + A084338(n-7).
G.f.: (x^2-2*x-2)/(x^3+x^2-1).
Showing 1-3 of 3 results.