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 1-7 of 7 results.

A000301 a(n) = a(n-1)*a(n-2) with a(0) = 1, a(1) = 2; also a(n) = 2^Fibonacci(n).

Original entry on oeis.org

1, 2, 2, 4, 8, 32, 256, 8192, 2097152, 17179869184, 36028797018963968, 618970019642690137449562112, 22300745198530623141535718272648361505980416, 13803492693581127574869511724554050904902217944340773110325048447598592
Offset: 0

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Author

N. J. A. Sloane, Mar 15 1996

Keywords

Comments

Continued fraction expansion of s = A073115 = 1.709803442861291... = Sum_{k >= 0} (1/2^floor(k * phi)) where phi is the golden ratio (1 + sqrt(5))/2. - Benoit Cloitre, Aug 19 2002
The continued fraction expansion of the above constant s is [1; 1, 2, 2, 4, ...], that of the rabbit constant r = s-1 = A014565 is [0; 1, 2, 2, 4, ...]. - M. F. Hasler, Nov 10 2018

References

  • Stephen Wolfram, A New Kind of Science, Wolfram Media, 2002, p. 913.

Crossrefs

Programs

  • Haskell
    a000301 = a000079 . a000045
    a000301_list = 1 : scanl (*) 2 a000301_list
    -- Reinhard Zumkeller, Mar 20 2013
    
  • Magma
    [2^Fibonacci(n): n in [0..20]]; // Vincenzo Librandi, Apr 18 2011
    
  • Maple
    A000301 := proc(n) option remember;
                 if n < 2 then 1+n
               else A000301(n-1)*A000301(n-2)
                 fi
               end:
    seq(A000301(n), n=0..15);
  • Mathematica
    2^Fibonacci[Range[0, 14]] (* Alonso del Arte, Jul 28 2016 *)
  • PARI
    a(n)=1<Charles R Greathouse IV, Jan 12 2012
    
  • SageMath
    [2^fibonacci(n) for n in range(15)] # G. C. Greubel, Jul 29 2024

Formula

a(n) ~ k^phi^n with k = 2^(1/sqrt(5)) = 1.3634044... and phi the golden ratio. - Charles R Greathouse IV, Jan 12 2012
a(n) = A000304(n+3) / A010098(n+1). - Reinhard Zumkeller, Jul 06 2014
Sum_{n>=0} 1/a(n) = A124091. - Amiram Eldar, Oct 27 2020
Limit_{n->oo} a(n)/a(n-1)^phi = 1. - Peter Woodward, Nov 24 2023

Extensions

Offset changed from 1 to 0 by Vincenzo Librandi, Apr 18 2011

A010098 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=3.

Original entry on oeis.org

1, 3, 3, 9, 27, 243, 6561, 1594323, 10460353203, 16677181699666569, 174449211009120179071170507, 2909321189362570808630465826492242446680483, 507528786056415600719754159741696356908742250191663887263627442114881
Offset: 0

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Author

Keywords

Comments

From Peter Bala, Nov 01 2013: (Start)
Let phi = (1/2)*(1 + sqrt(5)) denote the golden ratio A001622. This sequence gives the simple continued fraction expansion of the constant c := 2*Sum_{n>=1} 1/3^floor(n*phi) (= 4*Sum_{n>=1} floor(n/phi)/3^n) = 0.768597560593155198508 ... = 1/(1 + 1/(3 + 1/(3 + 1/(9 + 1/(27 + 1/(243 + 1/(6561 + ...))))))). The constant c is known to be transcendental (see Adams and Davison 1977). Cf. A014565.
Furthermore, for k = 0,1,2,... if we put X(k) = sum {n >= 1} 1/3^(n*Fibonacci(k) + Fibonacci(k+1)*floor(n*phi)) then the real number X(k+1)/X(k) has the simple continued fraction expansion [0; a(k+1), a(k+2), a(k+3), ...] (apply Bowman 1988, Corollary 1). (End)

Crossrefs

Programs

  • Haskell
    a010098 n = a010098_list !! n
    a010098_list = 1 : 3 : zipWith (*) a010098_list (tail a010098_list)
    -- Reinhard Zumkeller, Jul 06 2014
    
  • Magma
    [3^Fibonacci(n): n in [0..12]]; // G. C. Greubel, Jul 29 2024
    
  • Maple
    a[-1]:=1: a[0]:=3: a[1]:=3: for n from 2 to 13 do a[n]:=a[n-1]*a[n-2] od: seq(a[n], n=-1..10); # Zerinvary Lajos, Mar 19 2009
  • Mathematica
    3^Fibonacci[Range[0,13]] (* Vladimir Joseph Stephan Orlovsky, Jan 21 2012 *)
    RecurrenceTable[{a[0]==1,a[1]==3,a[n]==a[n-1]a[n-2]},a,{n,15}] (* Harvey P. Dale, Jan 21 2021 *)
  • SageMath
    [3^fibonacci(n) for n in range(13)] # G. C. Greubel, Jul 29 2024

Formula

a(n) = 3^Fibonacci(n).
a(n+1) = A000304(n+3) / A000301(n). - Reinhard Zumkeller, Jul 06 2014

A244003 A(n,k) = k^Fibonacci(n); square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 3, 2, 1, 0, 1, 4, 3, 4, 1, 0, 1, 5, 4, 9, 8, 1, 0, 1, 6, 5, 16, 27, 32, 1, 0, 1, 7, 6, 25, 64, 243, 256, 1, 0, 1, 8, 7, 36, 125, 1024, 6561, 8192, 1, 0, 1, 9, 8, 49, 216, 3125, 65536, 1594323, 2097152, 1, 0
Offset: 0

Views

Author

Alois P. Heinz, Jun 17 2014

Keywords

Examples

			Square array A(n,k) begins:
  1, 1,   1,    1,     1,      1,       1, ...
  0, 1,   2,    3,     4,      5,       6, ...
  0, 1,   2,    3,     4,      5,       6, ...
  0, 1,   4,    9,    16,     25,      36, ...
  0, 1,   8,   27,    64,    125,     216, ...
  0, 1,  32,  243,  1024,   3125,    7776, ...
  0, 1, 256, 6561, 65536, 390625, 1679616, ...
		

Crossrefs

Rows n=0, 1+2, 3-8 give: A000012, A001477, A000290, A000578, A000584, A001016, A010801, A010809.
Main diagonal gives: A152915.

Programs

  • Maple
    A:= (n, k)-> k^(<<1|1>, <1|0>>^n)[1, 2]:
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    A[0, 0] = 1; A[n_, k_] := k^Fibonacci[n]; Table[A[n-k, k], {n, 0, 12}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Nov 11 2015 *)

Formula

A(n,k) = k^A000045(n).
A(0,k) = 1, A(1,k) = k, A(n,k) = A(n-1,k) * A(n-2,k) for n>=2.

A010100 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=10.

Original entry on oeis.org

1, 10, 10, 100, 1000, 100000, 100000000, 10000000000000, 1000000000000000000000, 10000000000000000000000000000000000, 10000000000000000000000000000000000000000000000000000000
Offset: 0

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Author

Keywords

Comments

From Peter Bala, Nov 11 2013: (Start)
Let phi = 1/2*(1 + sqrt(5)) denote the golden ratio A001622. This sequence is the simple continued fraction expansion of the constant c := 9*sum {n = 1..inf} 1/10^floor(n*phi) (= 81*sum {n = 1..inf} floor(n/phi)/10^n) = 0.90990 90990 99090 99090 ... = 1/(1 + 1/(10 + 1/(10 + 1/(100 + 1/(1000 + 1/(100000 + 1/(100000000 + ...))))))). The constant c is known to be transcendental (see Adams and Davison 1977). Cf. A014565 and A005614.
Furthermore, for k = 0,1,2,... if we define the real number X(k) = sum {n >= 1} 1/10^(n*Fibonacci(k) + Fibonacci(k+1)*floor(n*phi)) then the real number X(k+1)/X(k) has the simple continued fraction expansion [0; a(k+1), a(k+2), a(k+3), ...] (apply Bowman 1988, Corollary 1). (End)

Crossrefs

Programs

  • Maple
    a:= n-> 10^(<<1|1>, <1|0>>^n)[1, 2]:
    seq(a(n), n=0..12);  # Alois P. Heinz, Jun 17 2014
  • Mathematica
    10^Fibonacci[Range[0,10]] (* Harvey P. Dale, Feb 12 2023 *)
  • PARI
    a(n) = 10^fibonacci(n); \\ Michel Marcus, Oct 25 2017

Formula

a(n) = 10^Fibonacci(n).

A214706 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=5.

Original entry on oeis.org

1, 5, 5, 25, 125, 3125, 390625, 1220703125, 476837158203125, 582076609134674072265625, 277555756156289135105907917022705078125, 161558713389263217748322010169914619837072677910327911376953125
Offset: 0

Views

Author

Vincenzo Librandi, Aug 01 2012

Keywords

Comments

a(17) has 1117 digits.
From Peter Bala, Nov 01 2013: (Start)
Let phi = 1/2*(1 + sqrt(5)) denote the golden ratio A001622. This sequence is the simple continued fraction expansion of the constant c := 4*Sum_{n = 1..oo} 1/5^floor(n*phi) (= 16*Sum_{n = 1..oo} floor(n/phi)/5^n) = 0.83866 83869 91037 14262 ... = 1/(1 + 1/(5 + 1/(5 + 1/(25 + 1/(125 + 1/(3125 + 1/(390625 + ...))))))). The constant c is known to be transcendental (see Adams and Davison 1977). Cf. A014565.
Furthermore, for k = 0,1,2,... if we define the real number X(k) = sum {n >= 1} 1/5^(n*Fibonacci(k) + Fibonacci(k+1)*floor(n*phi)) then the real number X(k+1)/X(k) has the simple continued fraction expansion [0; a(k+1), a(k+2), a(k+3), ...] (apply Bowman 1988, Corollary 1). (End)

Crossrefs

Programs

  • Magma
    [5^Fibonacci(n): n in [0..13]];
    
  • Maple
    a:= n-> 5^(<<1|1>, <1|0>>^n)[1, 2]:
    seq(a(n), n=0..12);  # Alois P. Heinz, Jun 17 2014
  • Mathematica
    5^Fibonacci[Range[0,11]]
    nxt[{a_,b_}]:={b,a*b}; NestList[nxt,{1,5},12][[All,1]] (* Harvey P. Dale, Oct 14 2018 *)
  • SageMath
    [5^fibonacci(n) for n in range(15)] # G. C. Greubel, Jan 07 2024

Formula

a(n) = 5^Fibonacci(n).

A214887 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=7.

Original entry on oeis.org

1, 7, 7, 49, 343, 16807, 5764801, 96889010407, 558545864083284007, 54116956037952111668959660849, 30226801971775055948247051683954096612865741943
Offset: 0

Views

Author

Vincenzo Librandi, Aug 01 2012

Keywords

Comments

a(17) has 1350 digits.
From Peter Bala, Nov 01 2013: (Start)
Let phi = 1/2*(1 + sqrt(5)) denote the golden ratio A001622. This sequence is the simple continued fraction expansion of the constant c := 6*sum {n = 1..inf} 1/7^floor(n*phi) (= 36*sum {n = 1..inf} floor(n/phi)/7^n) = 0.87718 67194 00499 51922 ... = 1/(1 + 1/(7 + 1/(7 + 1/(49 + 1/(343 + 1/(16807 + 1/(5764801 + ...))))))). The constant c is known to be transcendental (see Adams and Davison 1977). Cf. A014565.
Furthermore, for k = 0,1,2,... if we define the real number X(k) = sum {n >= 1} 1/7^(n*Fibonacci(k) + Fibonacci(k+1)*floor(n*phi)) then the real number X(k+1)/X(k) has the simple continued fraction expansion [0; a(k+1), a(k+2), a(k+3), ...] (apply Bowman 1988, Corollary 1). (End)

Crossrefs

Programs

  • Magma
    [7^Fibonacci(n): n in [0..10]];
  • Maple
    a:= n-> 7^(<<1|1>, <1|0>>^n)[1, 2]:
    seq(a(n), n=0..12);  # Alois P. Heinz, Jun 17 2014
  • Mathematica
    7^Fibonacci[Range[0,10]]
    nxt[{a_,b_}]:={b,a*b}; Transpose[NestList[nxt,{1,7},10]][[1]] (* Harvey P. Dale, Jun 10 2014 *)

Formula

a(n) = 7^Fibonacci(n).

A076776 a(0) = 1, a(1) = 2, a(2) = 5; for n > 2, a(n) = a(n-1)*a(n-2).

Original entry on oeis.org

1, 2, 5, 10, 50, 500, 25000, 12500000, 312500000000, 3906250000000000000, 1220703125000000000000000000000, 4768371582031250000000000000000000000000000000000
Offset: 0

Views

Author

Emily Shields (emilyshields_2001(AT)hotmail.com), Nov 14 2002

Keywords

Crossrefs

Programs

  • Maple
    with(combinat, fibonacci):A076776 := n->2^fibonacci(n-2)*5^fibonacci(n-1);
  • Mathematica
    nxt[{a_,b_}]:={b,a*b}; Join[{1},NestList[nxt,{2,5},15][[All,1]]] (* Harvey P. Dale, Jun 07 2021 *)

Formula

a(n) = 2^fibonacci(n-2)*5^fibonacci(n-1)for n>=2, fibonacci(n)=A000045(n). - Vladeta Jovovic and Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Nov 16 2002

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Nov 16 2002
Showing 1-7 of 7 results.