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 1-4 of 4 results.

A200676 Expansion of g.f. -(3*x^2-5*x+1)/(x^3-3*x^2+5*x-1).

Original entry on oeis.org

1, 0, 0, 1, 5, 22, 96, 419, 1829, 7984, 34852, 152137, 664113, 2899006, 12654828, 55241235, 241140697, 1052634608, 4594992184, 20058197793, 87558647021, 382213633910, 1668450426280, 7283169876691, 31792711738525, 138782499488832, 605817532105276
Offset: 0

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Author

Alois P. Heinz, Nov 21 2011

Keywords

Comments

Peter A. Lawrence (see links) has posted a challenge to find a 3x3 integer matrix with "smallish" elements whose powers generate a sequence that is not in the OEIS. This sequence is one of the solutions found.
The sequence without the first 3 entries (1, 5, 22, 96,...) are the partial sums of the partial sums of A049086. - R. J. Mathar, Jul 20 2025

Crossrefs

Programs

  • Maple
    a:= n-> (<<0|1|0>, <0|0|1>, <1|-3|5>>^n)[1, 1]:
    seq(a(n), n=0..30);
  • Mathematica
    CoefficientList[Series[-(3 x^2 - 5 x + 1)/(x^3 - 3 x^2 + 5 x - 1), {x, 0, 26}], x] (* Michael De Vlieger, Sep 04 2018 *)
    LinearRecurrence[{5,-3,1},{1,0,0},40] (* Harvey P. Dale, Aug 18 2021 *)

Formula

G.f.: -(3*x^2-5*x+1)/(x^3-3*x^2+5*x-1).
Term (1,1) in the 3x3 matrix [0,1,0; 0,0,1; 1,-3,5]^n.

A200752 Expansion of (-x^2 + 3*x - 1)/(x^3 - x^2 + 3*x - 1).

Original entry on oeis.org

1, 0, 0, 1, 3, 8, 22, 61, 169, 468, 1296, 3589, 9939, 27524, 76222, 211081, 584545, 1618776, 4482864, 12414361, 34378995, 95205488, 263651830, 730128997, 2021940649, 5599344780, 15506222688, 42941263933, 118916913891, 329315700428, 911971451326, 2525515567441
Offset: 0

Views

Author

Alois P. Heinz, Nov 21 2011

Keywords

Comments

Peter A. Lawrence (see links) has posted a challenge to find a 3x3 integer matrix with "smallish" elements whose powers generate a sequence that is not in the OEIS. This sequence is one of the solutions found.
a(n+3) is the number of ternary strings of length n in which the number of substrings of the form 0011 equals the number of substrings of the form 11. - John M. Campbell, Nov 02 2013

Crossrefs

Programs

  • Maple
    a:= n-> (<<0|1|0>, <0|0|1>, <1|-1|3>>^n)[1, 1]:
    seq(a(n), n=0..50);

Formula

G.f.: (-x^2+3*x-1)/(x^3-x^2+3*x-1).
Term (1,1) in the 3x3 matrix [0,1,0; 0,0,1; 1,-1,3]^n.
a(n) = 3*a(n-1) -a(n-2) +a(n-3) with a(0)=1, a(1)=0, a(2)=0. - Taras Goy, Jul 23 2017

A200715 Expansion of (-3*x^2 + x - 1)/(x^3 - 3*x^2 + x - 1).

Original entry on oeis.org

1, 0, 0, 1, 1, -2, -4, 3, 13, 0, -36, -23, 85, 118, -160, -429, 169, 1296, 360, -3359, -3143, 7294, 13364, -11661, -44459, 3888, 125604, 69481, -303443, -386282, 593528, 1448931, -717935, -4471200, -868464, 11827201, 9961393, -26388674, -44445652, 44681763
Offset: 0

Views

Author

Alois P. Heinz, Nov 21 2011

Keywords

Comments

Peter A. Lawrence (see links) has posted a challenge to find a 3 X 3 integer matrix with "smallish" elements whose powers generate a sequence that is not in the OEIS. This sequence is one of the solutions found.
|a(n)| is a prime number for n in {5, 7, 8, 11, 19, 27, 108, 276, 371, 608, ...} with values {2, 3, 13, 23, 3359, 69481, 167527749243856707416101, ...}.

Crossrefs

Programs

  • Maple
    a:= n-> (<<0|1|0>, <0|0|1>, <1|-3|1>>^n)[1, 1]:
    seq(a(n), n=0..50);
  • Mathematica
    CoefficientList[Series[(-3x^2+x-1)/(x^3-3x^2+x-1),{x,0,40}],x] (* or *) LinearRecurrence[{1,-3,1},{1,0,0},40] (* Harvey P. Dale, Nov 22 2011 *)
  • PARI
    Vec((-3*x^2+x-1)/(x^3-3*x^2+x-1)+O(x^99)) \\ Charles R Greathouse IV, Nov 22 2011

Formula

G.f.: (-3*x^2 + x - 1)/(x^3 - 3*x^2 + x - 1).
Term (1,1) in the 3 X 3 matrix [0,1,0; 0,0,1; 1,-3,1]^n.
a(n) = a(n-1) - 3*a(n-2) + a(n-3); a(0)=1, a(1)=a(2)=0. - Harvey P. Dale, Nov 22 2011

A353965 Number of tilings of a 3 X n rectangle using 2 X 2 and 1 X 1 tiles and right trominoes.

Original entry on oeis.org

1, 1, 13, 47, 259, 1189, 5877, 28167, 136723, 660173, 3194613, 15445007, 74699811, 361230229, 1746933205, 8448061879, 40854753875, 197572345789, 955455626773, 4620559362303, 22344915889827, 108059470995013, 522573007884725, 2527150465444071, 12221238828079379
Offset: 0

Views

Author

Gerhard Kirchner, May 13 2022

Keywords

Comments

For tiling algorithm see A351322.

Examples

			a(2) = 13:
    v    h,v   h=v   h,v
   ___   ___   ___   ___   ___
  |   | | |_| |  _| |  _| |_|_|    mirroring included
  |___| |___| |_| | |_|_| |_|_|    h: horizontal, v: vertical
  |_|_| |_|_| |___| |_|_| |_|_|
    2  +  4  +  2  +  4  +  1 = 13
		

Crossrefs

Programs

Formula

G.f.: (1 - 2*x + x^2) / (1 - 3*x - 9*x^2 + x^3 - 2*x^4).
a(n) = 3*a(n-1) + 9*a(n-2) - a(n-3) + 2*a(n-4).
31*a(n) = 18*(-2)^n +13*A200739(n+3) +2*A200739(n+2) +9*A200739(n+1). - R. J. Mathar, Jun 07 2025
Showing 1-4 of 4 results.