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 1-10 of 17 results. Next

A049666 a(n) = Fibonacci(5*n)/5.

Original entry on oeis.org

0, 1, 11, 122, 1353, 15005, 166408, 1845493, 20466831, 226980634, 2517253805, 27916772489, 309601751184, 3433536035513, 38078498141827, 422297015595610, 4683345669693537, 51939099382224517, 576013438874163224
Offset: 0

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Author

Keywords

Comments

For more information about this type of recurrence follow the Khovanova link and see A054413, A086902 and A178765. - Johannes W. Meijer, Jun 12 2010
For n >= 2, a(n) equals the permanent of the (n-1) X (n-1) tridiagonal matrix with 11's along the main diagonal and 1's along the subdiagonal and the superdiagonal. - John M. Campbell, Jul 08 2011
For n >= 1, a(n) equals the number of words of length n-1 on alphabet {0,1,...,11} avoiding runs of zeros of odd lengths. - Milan Janjic, Jan 28 2015
For n >= 1, a(n) equals the denominator of the continued fraction [11, 11, ..., 11] (with n copies of 11). The numerator of that continued fraction is a(n+1). - Greg Dresden and Shaoxiong Yuan, Jul 26 2019
From Michael A. Allen, Mar 30 2023: (Start)
Also called the 11-metallonacci sequence; the g.f. 1/(1-k*x-x^2) gives the k-metallonacci sequence.
a(n+1) is the number of tilings of an n-board (a board with dimensions n X 1) using unit squares and dominoes (with dimensions 2 X 1) if there are 11 kinds of squares available. (End)

Examples

			G.f. = x + 11*x^2 + 122*x^3 + 1353*x^4 + 15005*x^5 + 166408*x^6 + ...
		

Crossrefs

A column of array A028412.
Row n=11 of A073133, A172236 and A352361, and column k=11 of A157103.

Programs

  • Magma
    [Fibonacci(5*n)/5: n in [0..30]]; // G. C. Greubel, Dec 02 2017
  • Maple
    A049666 := proc(n)
        combinat[fibonacci](5*n)/5 ;
    end proc: # R. J. Mathar, May 07 2024
  • Mathematica
    Table[Fibonacci[5*n]/5, {n, 0, 100}] (* T. D. Noe, Oct 29 2009 *)
    a[ n_] := Fibonacci[n, 11]; (* Michael Somos, May 28 2014 *)
  • MuPAD
    numlib::fibonacci(5*n)/5 $ n = 0..25; // Zerinvary Lajos, May 09 2008
    
  • PARI
    a(n)=fibonacci(5*n)/5 \\ Charles R Greathouse IV, Feb 03 2014
    
  • Sage
    from sage.combinat.sloane_functions import recur_gen3
    it = recur_gen3(0,1,11,11,1,0)
    [next(it) for i in range(1,22)] # Zerinvary Lajos, Jul 09 2008
    
  • Sage
    [lucas_number1(n,11,-1) for n in range(0, 19)] # Zerinvary Lajos, Apr 27 2009
    
  • Sage
    [fibonacci(5*n)/5 for n in range(0, 19)] # Zerinvary Lajos, May 15 2009
    

Formula

G.f.: x/(1 - 11*x - x^2).
a(n) = A102312(n)/5.
a(n) = 11*a(n-1) + a(n-2) for n > 1, a(0)=0, a(1)=1. With a=golden ratio and b=1-a, a(n) = (a^(5n)-b^(5n))/(5*sqrt(5)). - Mario Catalani (mario.catalani(AT)unito.it), Jul 24 2003
a(n) = F(n, 11), the n-th Fibonacci polynomial evaluated at x=11. - T. D. Noe, Jan 19 2006
a(n) = ((11+sqrt(125))^n-(11-sqrt(125))^n)/(2^n*sqrt(125)). - Al Hakanson (hawkuu(AT)gmail.com), Jan 12 2009
From Johannes W. Meijer, Jun 12 2010: (Start)
a(2n) = 11*A049670(n), a(2n+1) = A097843(n).
a(3n+1) = A041227(5n), a(3n+2) = A041227(5n+3), a(3n+3) = 2*A041227(5n+4).
Limit_{k->oo} a(n+k)/a(k) = (A001946(n) + A049666(n)*sqrt(125))/2.
Limit_{n->oo} A001946(n)/A049666(n) = sqrt(125).
(End)
a(n) = F(n) + (-1)^n*5*F(n)^3 + 5*F(n)^5, n >= 0. See the D. Jennings formula given in a comment on A111125, where also the reference is given. - Wolfdieter Lang, Aug 31 2012
a(-n) = -(-1)^n * a(n). - Michael Somos, May 28 2014
E.g.f.: (exp((1/2)*(11-5*sqrt(5))*x)*(-1 + exp(5*sqrt(5)*x)))/(5*sqrt(5)). - Stefano Spezia, Aug 02 2019

A103134 a(n) = Fibonacci(6n+4).

Original entry on oeis.org

3, 55, 987, 17711, 317811, 5702887, 102334155, 1836311903, 32951280099, 591286729879, 10610209857723, 190392490709135, 3416454622906707, 61305790721611591, 1100087778366101931, 19740274219868223167, 354224848179261915075, 6356306993006846248183
Offset: 0

Views

Author

Creighton Dement, Jan 24 2005

Keywords

Comments

Gives those numbers which are Fibonacci numbers in A103135.
Generally, for any sequence where a(0)= Fibonacci(p), a(1) = F(p+q) and Lucas(q)*a(1) +- a(0) = F(p+2q), then a(n) = L(q)*a(n-1) +- a(n-2) generates the following Fibonacci sequence: a(n) = F(q(n)+p). So for this sequence, a(n) = 18*a(n-1) - a(n-2) = F(6n+4): q=6, because 18 is the 6th Lucas number (L(0) = 2, L(1)=1); F(4)=3, F(10)=55 and F(16)=987 (F(0)=0 and F(1)=1). See Lucas sequence A000032. This is a special case where a(0) and a(1) are increasing Fibonacci numbers and Lucas(m)*a(1) +- a(0) is another Fibonacci. - Bob Selcoe, Jul 08 2013
a(n) = x + y where x and y are solutions to x^2 = 5*y^2 - 1. (See related sequences with formula below.) - Richard R. Forberg, Sep 05 2013

Crossrefs

Programs

Formula

G.f.: (x+3)/(x^2-18*x+1).
a(n) = 18*a(n-1) - a(n-2) for n>1; a(0)=3, a(1)=55. - Philippe Deléham, Nov 17 2008
a(n) = A007805(n) + A075796(n), as follows from comment above. - Richard R. Forberg, Sep 05 2013
a(n) = ((15-7*sqrt(5)+(9+4*sqrt(5))^(2*n)*(15+7*sqrt(5))))/(10*(9+4*sqrt(5))^n). - Colin Barker, Jan 24 2016
a(n) = S(3*n+1, 3) = 3*S(n,18) + S(n-1,18), with the Chebyshev S polynomials (A049310), S(-1, x) = 0, and S(n, 18) = A049660(n+1). - Wolfdieter Lang, May 08 2023

Extensions

Edited by N. J. A. Sloane, Aug 10 2010

A134490 a(n) = Fibonacci(5n + 3).

Original entry on oeis.org

2, 21, 233, 2584, 28657, 317811, 3524578, 39088169, 433494437, 4807526976, 53316291173, 591286729879, 6557470319842, 72723460248141, 806515533049393, 8944394323791464, 99194853094755497, 1100087778366101931
Offset: 0

Views

Author

Artur Jasinski, Oct 28 2007

Keywords

Crossrefs

Programs

Formula

a(n) = 11a(n-1) + a(n-2). - Paul Curtz, May 07 2008
From R. J. Mathar, Nov 02 2008: (Start)
G.f.: (2-x)/(1 - 11x - x^2).
a(n) = |A122574(n+2)| + A049666(n+1). (End)
a(n) = A000045(A016885(n)). - Michel Marcus, Nov 08 2013

Extensions

Offset changed to 0 by R. J. Mathar, Jul 28 2008

A134504 a(n) = Fibonacci(7n + 6).

Original entry on oeis.org

8, 233, 6765, 196418, 5702887, 165580141, 4807526976, 139583862445, 4052739537881, 117669030460994, 3416454622906707, 99194853094755497, 2880067194370816120, 83621143489848422977, 2427893228399975082453
Offset: 0

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Author

Artur Jasinski, Oct 28 2007

Keywords

Crossrefs

Programs

Formula

G.f.: (-8-x) / (-1 + 29*x + x^2). - R. J. Mathar, Jul 04 2011
a(n) = A000045(A017053(n)). - Michel Marcus, Nov 08 2013
a(n) = 29*a(n-1) + a(n-2). - Wesley Ivan Hurt, Mar 15 2023

Extensions

Offset changed from 1 to 0 by Vincenzo Librandi, Apr 17 2011

A100334 An inverse Catalan transform of Fibonacci(2n).

Original entry on oeis.org

0, 1, 2, 2, 0, -5, -13, -21, -21, 0, 55, 144, 233, 233, 0, -610, -1597, -2584, -2584, 0, 6765, 17711, 28657, 28657, 0, -75025, -196418, -317811, -317811, 0, 832040, 2178309, 3524578, 3524578, 0, -9227465, -24157817, -39088169, -39088169, 0, 102334155, 267914296, 433494437, 433494437, 0, -1134903170
Offset: 0

Views

Author

Paul Barry, Nov 17 2004

Keywords

Crossrefs

Cf. A102312 (F(5n)), A134489 (F(5n+2)), A134490 (F(5n+3)).

Programs

  • Magma
    I:=[0,1,2,2]; [n le 4 select I[n] else 3*Self(n-1) -4*Self(n-2) +2*Self(n-3) -Self(n-4): n in [1..41]]; // G. C. Greubel, Jan 30 2023
    
  • Mathematica
    Table[FullSimplify[GoldenRatio^n*Sqrt[2/5 + 2*Sqrt[5]/25]*Sin[Pi*n/5 + Pi/5] - (1/GoldenRatio)^n*Sqrt[2/5 - 2*Sqrt[5]/25]*Sin[2*Pi*n/5 + 2*Pi/5]], {n, 0, 41}] (* Arkadiusz Wesolowski, Oct 26 2012 *)
    LinearRecurrence[{3,-4,2,-1}, {0,1,2,2}, 41] (* G. C. Greubel, Jan 30 2023 *)
  • SageMath
    def A100334(n): return sum((-1)^k*binomial(n-k,k)*fibonacci(2*n-2*k) for k in range(1+(n//2)))
    [A100334(n) for n in range(41)] # G. C. Greubel, Jan 30 2023

Formula

G.f.: x*(1-x)/(1-3*x+4*x^2-2*x^3+x^4).
a(n) = (phi)^n*sqrt(2/5+2*sqrt(5)/25)*sin(Pi*(n+1)/5) -(1/phi)^n*sqrt(2/5-2*sqrt(5)/25)*sin(2*Pi*(n+1)/5), where phi=(1+sqrt(5))/2;
a(n) = Sum_{k=0..floor(n/2)} (C(n-k, k)*(-1)^k*Sum_{j=0..n-k} C(n-k, j)*F(j));
a(n) = Sum_{k=0..floor(n/2)} C(n-k, k)*(-1)^k*Fibonacci(2n-2k).
a(n) = 3*a(n-1)-4*a(n-2)+2*a(n-3)-a(n-4). - Paul Curtz, May 13 2008
a(n) = Sum_{k=0..n} A109466(n,k)*A001906(k). - Philippe Deléham, Oct 30 2008
a(5*n) = -F(-5*n), a(5*n+1) = -F(-5*n-2), a(5*n+2) = a(5*n+3) = F(-5*n-3), a(5*n+4) = 0. - Ehren Metcalfe, Apr 04 2019

A134494 a(n) = Fibonacci(6n+2).

Original entry on oeis.org

1, 21, 377, 6765, 121393, 2178309, 39088169, 701408733, 12586269025, 225851433717, 4052739537881, 72723460248141, 1304969544928657, 23416728348467685, 420196140727489673, 7540113804746346429, 135301852344706746049, 2427893228399975082453
Offset: 0

Views

Author

Artur Jasinski, Oct 28 2007

Keywords

Crossrefs

Programs

  • Magma
    [Fibonacci(6*n +2): n in [0..100]]; // Vincenzo Librandi, Apr 17 2011
    
  • Maple
    seq( combinat[fibonacci](6*n+2),n=0..10) ; # R. J. Mathar, Apr 17 2011
  • Mathematica
    Table[Fibonacci[6n+2], {n, 0, 30}]
    Table[ChebyshevU[3*n, 3/2], {n, 0, 20}] (* Vaclav Kotesovec, May 27 2023 *)
  • PARI
    a(n)=fibonacci(6*n+2) \\ Charles R Greathouse IV, Jun 11 2015
    
  • PARI
    Vec((1+3*x)/(1-18*x+x^2) + O(x^100)) \\ Altug Alkan, Jan 24 2016

Formula

From R. J. Mathar, Jul 04 2011: (Start)
G.f.: ( 1+3*x ) / ( 1-18*x+x^2 ).
a(n) = 3*A049660(n)+A049660(n+1). (End)
a(n) = A000045(A016933(n)). - Michel Marcus, Nov 07 2013
a(n) = ((5-3*sqrt(5)+(5+3*sqrt(5))*(9+4*sqrt(5))^(2*n)))/(10*(9+4*sqrt(5))^n). - Colin Barker, Jan 24 2016
a(n) = S(3*n, 3) = S(n,18) + 3*S(n-1,18), with the Chebyshev S polynomials (A049310), S(-1, x) = 0, and S(n, 18) = A049660(n+1). - Wolfdieter Lang, May 08 2023

Extensions

Index in definition corrected by T. D. Noe, Joerg Arndt, Apr 17 2011

A138134 a(n) = Sum_{i=0..n} Fibonacci(5*i).

Original entry on oeis.org

0, 5, 60, 670, 7435, 82460, 914500, 10141965, 112476120, 1247379290, 13833648315, 153417510760, 1701426266680, 18869106444245, 209261597153380, 2320746675131430, 25737475023599115, 285432971934721700, 3165500166305537820
Offset: 0

Views

Author

Gary Detlefs, Dec 07 2010

Keywords

Comments

Partial sums of A102312.
Other sequences in the OEIS related to the sum of Fibonacci(k*n) (although not defined as such) are:
k = 1: A000071 = Fibonacci(n) - 1 (delete leading 0);
k = 2: A027941 = Fibonacci(2n+1) - 1;
k = 3: A099919 = (Fibonacci(3n+2) - 1)/2;
k = 4: A058038 = Fibonacci(2n)*Fibonacci(2n+2);
k = 6: A053606 = (Fibonacci(6n+3) - 2)/4.
These sequences appear to be second order linear inhomogeneous sequences of the form: a(0) = 0, a(1) = Fibonacci(k), a(n) = L(k)*a(n-1) + (-1)^(k+1)*a(n-2) + Fibonacci(k), where L(n) = A000032(n), n > 1.
The Koshy reference gives the closed form:
Sum_{i=0..n} Fibonacci(k*i) = (Fibonacci(n*k+k) - (-1)^k*Fibonacci(n*k) - Fibonacci(k))/(L(k) - (-1)^k - 1).

References

  • Thomas Koshy; Fibonacci and Lucas numbers with applications, Wiley,2001, p. 86.

Crossrefs

Programs

  • Maple
    with(combinat):fs5:=n-> sum(fibonacci(5*k),k=0..n):
    seq(fs5(n),n=0..18)
  • PARI
    a(n)=(fibonacci(5*n+5)+fibonacci(5*n)-5)/11 \\ Charles R Greathouse IV, Jun 11 2015

Formula

G.f.: 5*x/((x - 1)*(x^2 + 11*x - 1)). - R. J. Mathar, Dec 09 2010
a(n) = 11*a(n) + a(n-1) + 5, n > 1.
a(n) = 12*a(n-1) - 10*a(n-2) - a(n-3), n > 2.
a(n) = 1/11*(Fibonacci(5*n+5) + Fibonacci(5n) - 5).

A102310 Square array read by antidiagonals: Fibonacci(k*n).

Original entry on oeis.org

1, 1, 1, 2, 3, 2, 3, 8, 8, 3, 5, 21, 34, 21, 5, 8, 55, 144, 144, 55, 8, 13, 144, 610, 987, 610, 144, 13, 21, 377, 2584, 6765, 6765, 2584, 377, 21, 34, 987, 10946, 46368, 75025, 46368, 10946, 987, 34, 55, 2584, 46368, 317811, 832040, 832040, 317811, 46368, 2584, 55
Offset: 1

Views

Author

Ralf Stephan, Jan 06 2005

Keywords

Examples

			1,  1,   2,    3,     5, ...
1,  3,   8,   21,    55, ...
2,  8,  34,  144,   610, ...
3, 21, 144,  987,  6765, ...
5, 55, 610, 6765, 75025, ...
		

References

  • R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. 2nd Edition. Addison-Wesley, Reading, MA, 1994, p. 294.

Crossrefs

Equals A000045(A003991(k, n)).
Columns include A000045, A001906, A014445, A033888, A102312.
Main diagonal is in A054783. Antidiagonal sums are in A102311.

Programs

  • Magma
    /* As triangle */ [[Fibonacci(k*(n-k+1)): k in [1..n]]: n in [1.. 15]]; // Vincenzo Librandi, Jul 04 2019
  • Mathematica
    Table[Fibonacci[k*(n-k+1)], {n, 1, 10}, {k, 1, n}] // Flatten (* Jean-François Alcover, Jun 10 2017 *)
  • Sage
    F = fibonacci # A000045
    def A(n, k):
        return F((n-1)*k)*F(k+1) + F((n-1)*k - 1)*F(k)
    [A(n, k) for d in (1..10) for n, k in zip((d..1, step=-1), (1..d))] # Freddy Barrera, Jun 24 2019
    

Formula

For prime p, the formula holds: Fibonacci(k*p) = Fibonacci(p) * Sum_{i=0..floor((k-1)/2)} C(k-i-1, i)*(-1)^(i*p+i)*Lucas(p)^(k-2i-1).
A(n, k) = F((n-1)*k)*F(k+1) + F((n-1)*k-1)*F(k), where F(n) = A000045(n). - Freddy Barrera, Jun 24 2019

A134501 a(n) = Fibonacci(7n + 3).

Original entry on oeis.org

2, 55, 1597, 46368, 1346269, 39088169, 1134903170, 32951280099, 956722026041, 27777890035288, 806515533049393, 23416728348467685, 679891637638612258, 19740274219868223167, 573147844013817084101, 16641027750620563662096
Offset: 0

Views

Author

Artur Jasinski, Oct 28 2007

Keywords

Crossrefs

Programs

Formula

From R. J. Mathar, Jul 04 2011: (Start)
G.f.: (-2+3*x) / (-1 + 29*x + x^2).
a(n) = 2*A049667(n+1) - 3*A049667(n). (End)
a(n) = A000045(A017017(n)). - Michel Marcus, Nov 07 2013

Extensions

Offset changed to 0 by Vincenzo Librandi, Apr 16 2011

A134502 a(n) = Fibonacci(7n + 4).

Original entry on oeis.org

3, 89, 2584, 75025, 2178309, 63245986, 1836311903, 53316291173, 1548008755920, 44945570212853, 1304969544928657, 37889062373143906, 1100087778366101931, 31940434634990099905, 927372692193078999176, 26925748508234281076009
Offset: 0

Views

Author

Artur Jasinski, Oct 28 2007

Keywords

Crossrefs

Programs

Formula

From R. J. Mathar, Jul 04 2011: (Start)
G.f.: (-3-2*x) / (-1 + 29*x + x^2).
a(n) = 2*A049667(n) + 3*A049667(n+1). (End)
a(n) = A000045(A017029(n)). - Michel Marcus, Nov 07 2013

Extensions

Offset changed from 1 to 0 by Vincenzo Librandi, Apr 17 2011
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