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 12 results. Next

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

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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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

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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

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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).

A215270 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=6.

Original entry on oeis.org

1, 6, 6, 36, 216, 7776, 1679616, 13060694016, 21936950640377856, 286511799958070431838109696, 6285195213566005335561053533150026217291776, 1800782593726645086383198950649858141454002621435149880441896326660096
Offset: 0

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Author

Bruno Berselli, Aug 07 2012

Keywords

Comments

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 := 5*sum {n = 1..inf} 1/6^floor(n*phi) (= 25*sum {n = 1..inf} floor(n/phi)/6^n) = 0.86045 01626 86090 61353 ... = 1/(1 + 1/(6 + 1/(6 + 1/(36 + 1/(216 + 1/(7776 + 1/(1679616 + ...))))))). 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} 1/6^(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

Cf. A166470 (same recurrence with initial values 2, 6). A014565.
Column k=6 of A244003.

Programs

  • Magma
    [6^Fibonacci(n): n in [0..11]];
  • Maple
    a:= n-> 6^(<<1|1>, <1|0>>^n)[1, 2]:
    seq(a(n), n=0..12);  # Alois P. Heinz, Jun 17 2014
  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 6, a[n] == a[n - 1] a[n - 2]}, a[n], {n, 0, 15}]

Formula

a(n) = 6^Fibonacci(n).

A215271 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=8.

Original entry on oeis.org

1, 8, 8, 64, 512, 32768, 16777216, 549755813888, 9223372036854775808, 5070602400912917605986812821504, 46768052394588893382517914646921056628989841375232, 237142198758023568227473377297792835283496928595231875152809132048206089502588928
Offset: 0

Views

Author

Bruno Berselli, Aug 07 2012

Keywords

Comments

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 := 7*sum {n = 1..inf} 1/8^floor(n*phi) (= 49*sum {n = 1..inf} floor(n/phi)/8^n) = 0.89040 80325 60827 28336 ... = 1/(1 + 1/(8 + 1/(8 + 1/(64 + 1/(512 + 1/(32768 + 1/(16777216 + ...))))))). 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} 1/8^(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
    [8^Fibonacci(n): n in [0..11]];
  • Maple
    a:= n-> 8^(<<1|1>, <1|0>>^n)[1, 2]:
    seq(a(n), n=0..12);  # Alois P. Heinz, Jun 17 2014
  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 8, a[n] == a[n - 1] a[n - 2]}, a[n], {n, 0, 15}]

Formula

a(n) = 8^Fibonacci(n).

A215272 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=9.

Original entry on oeis.org

1, 9, 9, 81, 729, 59049, 43046721, 2541865828329, 109418989131512359209, 278128389443693511257285776231761, 30432527221704537086371993251530170531786747066637049
Offset: 0

Views

Author

Bruno Berselli, Aug 07 2012

Keywords

Comments

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 := 8*sum {n = 1..inf} 1/9^floor(n*phi) (= 64*sum {n = 1..inf} floor(n/phi)/9^n) = 0.90109 74122 99938 29901 ... = 1/(1 + 1/(9 + 1/(9 + 1/(81 + 1/(729 + 1/(59049 + 1/(43046721 + ...))))))). 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} 1/9^(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
    [9^Fibonacci(n): n in [0..10]];
    
  • Maple
    a:= n-> 9^(<<1|1>, <1|0>>^n)[1, 2]:
    seq(a(n), n=0..12);  # Alois P. Heinz, Jun 17 2014
  • Mathematica
    RecurrenceTable[{a[0] == 1, a[1] == 9, a[n] == a[n - 1] a[n - 2]}, a[n], {n, 0, 15}]
  • PARI
    a(n) = 9^fibonacci(n); \\ Jinyuan Wang, Apr 06 2019

Formula

a(n) = 9^Fibonacci(n).

A000304 a(n) = a(n-1)*a(n-2).

Original entry on oeis.org

2, 3, 6, 18, 108, 1944, 209952, 408146688, 85691213438976, 34974584955819144511488, 2997014624388697307377363936018956288, 104819342594514896999066634490728502944926883876041385836544
Offset: 2

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Author

Keywords

Comments

A038500(a(n)) = A010098(n-2); for n > 2: A006519(a(n)) = A000301(n-3); A001222(a(n)) = A000045(n-1). - Reinhard Zumkeller, Jul 06 2014

Crossrefs

Programs

  • Haskell
    a000304 n = a000304_list !! (n-2)
    a000304_list = 2 : 3 : zipWith (*) a000304_list (tail a000304_list)
    -- Reinhard Zumkeller, Jul 06 2014
  • Maple
    A000304 := proc(n) option remember; if n <=3 then n else A000304(n-1)*A000304(n-2); fi; end;
  • Mathematica
    nxt[{a_,b_}]:={b,a*b}; Transpose[NestList[nxt,{2,3},12]][[1]] (* Harvey P. Dale, Nov 16 2014 *)

Formula

For n>=4, a(n) = 2^A000045(n-3)*3^A000045(n-2). - Benoit Cloitre, Sep 26 2003
For n > 2: a(n) = A000301(n-3) * A010098(n-2). - Reinhard Zumkeller, Jul 06 2014

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Feb 17 2010

A010099 a(n) = a(n-1)*a(n-2) with a(0)=1, a(1)=4.

Original entry on oeis.org

1, 4, 4, 16, 64, 1024, 65536, 67108864, 4398046511104, 295147905179352825856, 1298074214633706907132624082305024, 383123885216472214589586756787577295904684780545900544
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 is the simple continued fraction expansion of the constant c := 3*sum {n = 1..inf} 1/4^floor(n*phi) (= 9*sum {n = 1..inf} floor(n/phi)/4^n) = 0.80938 42984 64421 90504 ... = 1/(1 + 1/(4 + 1/(4 + 1/(16 + 1/(64 + 1/(1024 + 1/(65536 + ...))))))). 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} 1/4^(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[ -1]:=1:a[0]:=4: a[1]:=4: 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

Formula

a(n) = 4^Fibonacci(n).
Showing 1-10 of 12 results. Next