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 1-6 of 6 results.

A111573 a(n) = a(n-1) + a(n-3) + a(n-4), n >= 4, with initial terms 0,1,3,3.

Original entry on oeis.org

0, 1, 3, 3, 4, 8, 14, 21, 33, 55, 90, 144, 232, 377, 611, 987, 1596, 2584, 4182, 6765, 10945, 17711, 28658, 46368, 75024, 121393, 196419, 317811, 514228, 832040, 1346270, 2178309, 3524577, 5702887, 9227466, 14930352, 24157816, 39088169
Offset: 0

Views

Author

Creighton Dement, Aug 10 2005

Keywords

Comments

See comment and FAMP code for A111569.

Crossrefs

Programs

  • Mathematica
    Table[Fibonacci[n + 1] - Cos[n*Pi/2], {n, 0, 40}] (* Greg Dresden, Oct 16 2021 *)

Formula

G.f.: -x*(1+2*x)/((x^2+x-1)*(x^2+1)).
a(n) = A056594(n+3) + A000045(n+1). - R. J. Mathar, Nov 10 2009
From Greg Dresden, Jan 15 2024: (Start)
a(2*n) = Fibonacci(n)*Lucas(n+1);
a(2*n+1) = Fibonacci(2*n+1). (End)

Extensions

Name clarified by Robert C. Lyons, Feb 06 2025

A111570 a(n) = a(n-1) + a(n-3) + a(n-4), n >= 4, with initial terms 2,5,4,7.

Original entry on oeis.org

2, 5, 4, 7, 14, 23, 34, 55, 92, 149, 238, 385, 626, 1013, 1636, 2647, 4286, 6935, 11218, 18151, 29372, 47525, 76894, 124417, 201314, 325733, 527044, 852775, 1379822, 2232599, 3612418, 5845015, 9457436, 15302453, 24759886
Offset: 0

Views

Author

Creighton Dement, Aug 10 2005

Keywords

Comments

See comment and FAMP code for A111569.
Floretion Algebra Multiplication Program, FAMP Code: 1vesseq[B+H] with B = - .25'i + .25'j - .25i' + .25j' + k' - .5'kk' - .25'ik' - .25'jk' - .25'ki' - .25'kj' - .5e and H = + .75'ii' + .75'jj' + .75'kk' + .75e

Crossrefs

Formula

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

Extensions

Name clarified by Robert C. Lyons, Feb 06 2025

A111571 a(n) = a(n-1) + a(n-3) + a(n-4), n >= 4, with initial terms 1,1,-2,-1.

Original entry on oeis.org

1, 1, -2, -1, 1, 0, -3, -3, -2, -5, -11, -16, -23, -39, -66, -105, -167, -272, -443, -715, -1154, -1869, -3027, -4896, -7919, -12815, -20738, -33553, -54287, -87840, -142131, -229971, -372098, -602069, -974171, -1576240, -2550407, -4126647, -6677058, -10803705
Offset: 0

Views

Author

Creighton Dement, Aug 10 2005

Keywords

Comments

See comment and FAMP code for A111569.
Floretion Algebra Multiplication Program, FAMP Code: 1jesseq[B+H] with B = - .25'i + .25'j - .25i' + .25j' + k' - .5'kk' - .25'ik' - .25'jk' - .25'ki' - .25'kj' - .5e and H = + .75'ii' + .75'jj' + .75'kk' + .75e

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{1,0,1,1},{1,1,-2,-1},40] (* or *) CoefficientList[ Series[ (-1+3*x^2)/((1+x^2)*(x^2+x-1)),{x,0,40}],x]  (* Harvey P. Dale, Apr 23 2011 *)

Formula

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

Extensions

Name clarified by Robert C. Lyons, Feb 06 2025

A111572 a(n) = a(n-1) + a(n-3) + a(n-4), n >= 4, with initial terms -1,3,2,1.

Original entry on oeis.org

-1, 3, 2, 1, 3, 8, 11, 15, 26, 45, 71, 112, 183, 299, 482, 777, 1259, 2040, 3299, 5335, 8634, 13973, 22607, 36576, 59183, 95763, 154946, 250705, 405651, 656360, 1062011, 1718367, 2780378, 4498749, 7279127, 11777872, 19056999, 30834875, 49891874, 80726745
Offset: 0

Views

Author

Creighton Dement, Aug 10 2005

Keywords

Comments

See comment and FAMP code for A111569.
Floretion Algebra Multiplication Program, FAMP Code: 4ibaseseq[B+H] with B = - .25'i + .25'j - .25i' + .25j' + k' - .5'kk' - .25'ik' - .25'jk' - .25'ki' - .25'kj' - .5e and H = + .75'ii' + .75'jj' + .75'kk' + .75e
From Greg Dresden and Jiaqi Wang, Jun 24 2023: (Start)
For n >= 5, a(n) is also the number of ways to tile this "central staircase" figure of length n-2 with squares and dominoes. This is the picture for length 9; there are a(11)=112 ways to tile it:
_
|||_|||_|||_|
|_| (End)

Crossrefs

Formula

G.f.: (1-4*x+x^2)/((1+x^2)*(x^2+x-1))
From Greg Dresden and Jiaqi Wang, Jun 24 2023: (Start)
a(2*n) = F(n+1)*L(n-1) + F(n)*F(n-1),
a(2*n+1) = F(n+1)*(F(n+1) + 2*F(n-1)), for F(n) and L(n) the Fibonacci and Lucas numbers.
(End)

Extensions

Name clarified by Robert C. Lyons, Feb 06 2025

A260259 a(n) = F(n)*F(n+1) - (-1)^n, where F = A000045.

Original entry on oeis.org

-1, 2, 1, 7, 14, 41, 103, 274, 713, 1871, 4894, 12817, 33551, 87842, 229969, 602071, 1576238, 4126649, 10803703, 28284466, 74049689, 193864607, 507544126, 1328767777, 3478759199, 9107509826, 23843770273, 62423800999, 163427632718, 427859097161, 1120149658759
Offset: 0

Views

Author

Bruno Berselli, Oct 31 2015

Keywords

Comments

Primes in sequence for n = 1, 3, 5, 6, 9, 24, 42, 48, 53, 71, 86, 102, 138, 182, 302, 438, 506, 926, ...

Crossrefs

First bisection of A111569.
Cf. A226205: numbers of the form F(n)*F(n+1)+(-1)^n.
Cf. A000045, A001654, A003482, A059929, A089508 (first bisection, without -1), A206351.

Programs

  • Magma
    [Fibonacci(n)*Fibonacci(n+1)-(-1)^n: n in [0..30]];
  • Maple
    with(combinat): A260259:=n->fibonacci(n)*fibonacci(n+1)-(-1)^n: seq(A260259(n), n=0..50); # Wesley Ivan Hurt, Feb 04 2017
  • Mathematica
    Table[Fibonacci[n] Fibonacci[n + 1] - (-1)^n, {n, 0, 30}]
  • Maxima
    makelist(fib(n)*fib(n+1)-(-1)^n,n,0,30);
    
  • PARI
    for(n=0, 30, print1(fibonacci(n)*fibonacci(n+1)-(-1)^n", "));
    
  • PARI
    a(n) = round((2^(-1-n)*(-3*(-1)^n*2^(2+n)-(3-sqrt(5))^n*(-1+sqrt(5))+(1+sqrt(5))*(3+sqrt(5))^n))/5) \\ Colin Barker, Sep 29 2016
    
  • PARI
    Vec(-(1-4*x+x^2)/((1+x)*(1-3*x+x^2)) + O(x^30)) \\ Colin Barker, Sep 29 2016
    
  • Sage
    [fibonacci(n)*fibonacci(n+1)-(-1)^n for n in (0..30)]
    

Formula

G.f.: (-1 + 4*x - x^2)/((1 + x)*(1 - 3*x + x^2)).
a(n) = -a(-n-1) = 2*a(n-1) + 2*a(n-2) - a(n-3) for all n in Z.
a(n) = F(n+2)^2 - 2*F(n+1)^2.
a(n) = A059929(n) - A059929(n-1) with A059929(-1)=1.
a(n) = -A001654(n+1) + 4*A001654(n) - A001654(n-1).
a(n) = A206351((n+2)/2)-2 for even n; a(n) = A003482((n-1)/2)+2 for odd n.
Sum_{i>=0} 1/a(i) = .754301907697893871765121109686...
a(n) = (2^(-1-n)*(-3*(-1)^n*2^(2+n)-(3-sqrt(5))^n*(-1+sqrt(5))+(1+sqrt(5))*(3+sqrt(5))^n))/5. - Colin Barker, Sep 29 2016

A111574 a(n) = a(n-1) + a(n-3) + a(n-4), n >= 4, with initial terms 1,-1,2,3.

Original entry on oeis.org

1, -1, 2, 3, 3, 4, 9, 15, 22, 35, 59, 96, 153, 247, 402, 651, 1051, 1700, 2753, 4455, 7206, 11659, 18867, 30528, 49393, 79919, 129314, 209235, 338547, 547780, 886329, 1434111, 2320438, 3754547, 6074987, 9829536, 15904521, 25734055, 41638578, 67372635
Offset: 0

Views

Author

Creighton Dement, Aug 10 2005

Keywords

Comments

See comment and FAMP code for A111569.
Floretion Algebra Multiplication Program, FAMP Code: -4baseiseq[B+H] with B = - .25'i + .25'j - .25i' + .25j' + k' - .5'kk' - .25'ik' - .25'jk' - .25'ki' - .25'kj' - .5e and H = + .75'ii' + .75'jj' + .75'kk' + .75e

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{1,0,1,1},{1,-1,2,3},40] (* Harvey P. Dale, Jan 24 2017 *)

Formula

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

Extensions

Name clarified by Robert C. Lyons, Feb 06 2025
Showing 1-6 of 6 results.