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.

A190995 Fibonacci sequence beginning 9, 7.

Original entry on oeis.org

9, 7, 16, 23, 39, 62, 101, 163, 264, 427, 691, 1118, 1809, 2927, 4736, 7663, 12399, 20062, 32461, 52523, 84984, 137507, 222491, 359998, 582489, 942487, 1524976, 2467463, 3992439, 6459902, 10452341, 16912243, 27364584, 44276827, 71641411, 115918238, 187559649
Offset: 0

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Comments

From Wajdi Maaloul, Jun 20 2022: (Start)
For n>0, 2*a(n) is the number of ways to tile this figure below with squares and dominoes (a strip of length n+1 that begins with a length 3 vertical strip and length 4 one).
_
||
|||
|||_______ _
|||_|||_|...|_|
(End)

Crossrefs

Programs

  • Magma
    [n le 2 select 11-2*n else Self(n-1)+Self(n-2): n in [1..50]]; // Vincenzo Librandi, Feb 15 2012
    
  • Maple
    a:= n-> (<<0|1>, <1|1>>^n. <<9, 7>>)[1, 1]:
    seq(a(n), n=0..36);  # Alois P. Heinz, Oct 26 2022
  • Mathematica
    LinearRecurrence[{1, 1}, {9, 7}, 100]
  • PARI
    a(n)=7*fibonacci(n)+9*fibonacci(n-1) \\ Charles R Greathouse IV, Jun 08 2011
    
  • SageMath
    [7*fibonacci(n) + 9*fibonacci(n-1) for n in range(51)] # G. C. Greubel, Oct 26 2022

Formula

a(n) = ((9+sqrt(5))/2)*((1+sqrt(5))/2)^n + ((9-sqrt(5))/2)*((1-sqrt(5))/2)^n. - Antonio Alberto Olivares
G.f.: (9-2*x)/(1-x-x^2). - Colin Barker, Jan 11 2012
a(n) = 7*Fibonacci(n) + 9*Fibonacci(n-1) = 7*Fibonacci(n+1) + 2*Fibonacci(n-1) = 7*Lucas(n) - 5*Fibonacci(n-1) for n>0. - Wajdi Maaloul, Jun 20 2022

A294116 Fibonacci sequence beginning 2, 21.

Original entry on oeis.org

2, 21, 23, 44, 67, 111, 178, 289, 467, 756, 1223, 1979, 3202, 5181, 8383, 13564, 21947, 35511, 57458, 92969, 150427, 243396, 393823, 637219, 1031042, 1668261, 2699303, 4367564, 7066867, 11434431, 18501298, 29935729, 48437027, 78372756, 126809783, 205182539, 331992322, 537174861
Offset: 0

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Bruno Berselli, Oct 23 2017

Keywords

References

  • Steven Vajda, Fibonacci and Lucas Numbers, and the Golden Section: Theory and Applications, Dover Publications (2008), page 24 (formula 8).

Crossrefs

Subsequence of A047201, A047592, A113763.
Sequences of the type g(2,k;n): A118658 (k=0), A000032 (k=1), 2*A000045 (k=2,4), A020695 (k=3), A001060 (k=5), A022112 (k=6), A022113 (k=7), A294157 (k=8), A022114 (k=9), A022367 (k=10), A022115 (k=11), A022368 (k=12), A022116 (k=13), A022369 (k=14), A022117 (k=15), A022370 (k=16), A022118 (k=17), A022371 (k=18), A022119 (k=19), A022372 (k=20), this sequence (k=21), A022373 (k=22); A022374 (k=24); A022375 (k=26); A022376 (k=28), A190994 (k=29), A022377 (k=30); A022378 (k=32).

Programs

  • Magma
    a0:=2; a1:=21; [GeneralizedFibonacciNumber(a0, a1, n): n in [0..40]];
    
  • Mathematica
    LinearRecurrence[{1, 1}, {2, 21}, 40]
  • PARI
    Vec((2 + 19*x)/(1 - x - x^2) + O(x^40)) \\ Colin Barker, Oct 25 2017
    
  • Sage
    a = BinaryRecurrenceSequence(1, 1, 2, 21)
    print([a(n) for n in range(38)]) # Peter Luschny, Oct 25 2017

Formula

G.f.: (2 + 19*x)/(1 - x - x^2).
a(n) = a(n-1) + a(n-2).
Let g(r,s;n) be the n-th generalized Fibonacci number with initial values r, s. We have:
a(n) = Lucas(n) + g(0,20;n), see A022354;
a(n) = Fibonacci(n) + g(2,20;n), see A022372;
a(n) = 2*g(1,21;n) - g(0,21;n);
a(n) = g(1,k;n) + g(1,21-k;n) for all k in Z.
a(h+k) = a(h)*Fibonacci(k-1) + a(h+1)*Fibonacci(k) for all h, k in Z (see S. Vajda in References section). For h=0 and k=n:
a(n) = 2*Fibonacci(n-1) + 21*Fibonacci(n).
Sum_{j=0..n} a(j) = a(n+2) - 21.
a(n) = (2^(-n)*((1-sqrt(5))^n*(-20+sqrt(5)) + (1+sqrt(5))^n*(20+sqrt(5)))) / sqrt(5). - Colin Barker, Oct 25 2017

A190996 Fibonacci sequence beginning 10, 7.

Original entry on oeis.org

10, 7, 17, 24, 41, 65, 106, 171, 277, 448, 725, 1173, 1898, 3071, 4969, 8040, 13009, 21049, 34058, 55107, 89165, 144272, 233437, 377709, 611146, 988855, 1600001, 2588856, 4188857, 6777713, 10966570, 17744283, 28710853, 46455136, 75165989, 121621125
Offset: 0

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For n >= 5, the number a(n-3) is the dimension of a commutative Hecke algebra of affine type D_n with independent parameters. See Theorem 1.4, Corollary 1.5, and the table on page 524 in the link "Hecke algebras with independent parameters". - Jia Huang, Jan 20 2019
From Greg Dresden and Yiming Wu, Sep 10 2023: (Start)
For n >= 3, a(n) is the number of ways to tile this shape of length n+2 with squares and dominos:
||___________________||
|||_|||_|||_|||_|||
|| ||. (End)
For n >= 3, a(n) is the number of edge covers of the kayak paddle graphs KP(3,3,n-3), where we interpret KP(3,3,0) as two C_3's with one common vertex. - Feryal Alayont, Sep 28 2024

Crossrefs

Programs

  • Magma
    [n le 2 select 13-3*n else Self(n-1)+Self(n-2): n in [1..50]]; // Vincenzo Librandi, Feb 15 2012
    
  • Maple
    seq(coeff(series((10-3*x)/(1-x-x^2),x,n+1), x, n), n = 0 .. 40); # Muniru A Asiru, Jan 22 2019
  • Mathematica
    LinearRecurrence[{1, 1}, {10, 7}, 100]
  • PARI
    a(n)=7*fibonacci(n)+10*fibonacci(n-1) \\ Charles R Greathouse IV, Jun 08 2011
    
  • SageMath
    [7*fibonacci(n+1) +3*fibonacci(n-1) for n in range(51)] # G. C. Greubel, Oct 26 2022

Formula

a(n) = (5 + 2*sqrt(5)/5)*((1 + sqrt(5))/2)^n + (5 - 2*sqrt(5)/5)*((1 - sqrt(5))/2)^n. - Antonio Alberto Olivares, Jun 07 2011
a(n) = 7*Fibonacci(n) + 10*Fibonacci(n-1). - Charles R Greathouse IV, Jun 08 2011
G.f.: (10-3*x)/(1-x-x^2). - Colin Barker, Jan 11 2012
a(n) = 4*Fibonacci(n+1) + 3*LucasL(n). - G. C. Greubel, Oct 26 2022
a(n) = A000285(n)+3*A000285(n-1). - Feryal Alayont, Sep 28 2024
a(2*n) = A000285(n)^2 + A000285(n-1)^2. - Greg Dresden, Feb 28 2025
Showing 1-3 of 3 results.