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 11 results. Next

A144288 Fibonacci rabbit sequence number n coded in base n, also diagonal of A144287.

Original entry on oeis.org

1, 2, 10, 276, 81901, 2247615258, 81658169024988865, 644986443956439734064225751112, 3427833941153173630835645403655873661712817810325122
Offset: 1

Views

Author

Alois P. Heinz, Sep 17 2008

Keywords

Crossrefs

Programs

  • Maple
    f:= proc(n, b) option remember; `if`(n<2, [n, n], [f(n-1, b)[1] *b^f(n-1, b)[2] +f(n-2, b)[1], f(n-1, b)[2] +f(n-2, b)[2]]) end: a:= n-> f(n, n)[1]: seq(a(n), n=1..11);
  • Mathematica
    f[n_, b_] := f[n, b] = If[n < 2, {n, n}, {f[n-1, b][[1]]*b^f[n-1, b][[2]] + f[n-2, b][[1]], f[n-1, b][[2]] + f[n-2, b][[2]]}]; a[n_] := f[n, n][[1]]; Table[a[n], {n, 1, 9}] (* Jean-François Alcover, Jan 03 2013, translated from Maple *)

Formula

See program.

A005203 Fibonacci numbers (or rabbit sequence) converted to decimal.

Original entry on oeis.org

0, 1, 2, 5, 22, 181, 5814, 1488565, 12194330294, 25573364166211253, 439347050970302571643057846, 15829145720289447797800874537321282579904181, 9797766637414564027586288536574448245991597197836000123235901011048118
Offset: 0

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Author

Keywords

Comments

a(n) is also the denominator of the continued fraction [2^F(0), 2^F(1), 2^F(2), 2^F(3), 2^F(4), ..., 2^F(n-1)] for n>0. For the numerator, see A063896. - Chinmay Dandekar and Greg Dresden, Sep 11 2020

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    rewrite_0to1_1to10_n_i_times := proc(n,i) local z,j; z := n; j := i; while(j > 0) do z := rewrite_0to1_1to10(z); j := j - 1; od; RETURN(z); end;
    rewrite_0to1_1to10 := proc(n) option remember; if(n < 2) then RETURN(n + 1); else RETURN(((2^(1+(n mod 2))) * rewrite_0to1_1to10(floor(n/2))) + (n mod 2) + 1); fi; end;
  • Mathematica
    a[0] = 0; a[1] = 1; a[n_] := a[n] = a[n-1]*2^Fibonacci[n-1] + a[n-2]; Table[a[n], {n, 0, 12}] (* Jean-François Alcover, Jul 27 2011 *)
  • Python
    def A005203(n):
        s = '0'
        for i in range(n):
            s = s.replace('0','a').replace('1','10').replace('a','1')
        return int(s,2) # Chai Wah Wu, Apr 24 2025

Formula

a(0) = 0, a(1) = 1, a(n) = a(n-1) * 2^F(n-1) + a(n-2).
a(n) = rewrite_0to1_1to10_n_i_times(0, n) [ Each 0->1, 1->10 in binary expansion ]

Extensions

Comments and more terms from Antti Karttunen, Mar 30 1999

A036299 Binary Fibonacci (or rabbit) sequence.

Original entry on oeis.org

1, 10, 101, 10110, 10110101, 1011010110110, 101101011011010110101, 1011010110110101101011011010110110, 1011010110110101101011011010110110101101011011010110101
Offset: 0

Views

Author

Keywords

Comments

A055642(a(n)) = A000045(n+2). - Reinhard Zumkeller, Jul 06 2014

References

  • N. G. De Bruijn, (1989, January). Updown generation of Beatty sequences. Koninklijke Nederlandsche Akademie van Wetenschappen (Indationes Math.), Proc., Ser. A, 92:4 (1968), 385-407. See Fig. 3.
  • J. Kappraff, D. Blackmore and G. Adamson, Phyllotaxis as a dynamical system: a study in number, Chap. 17 of Jean and Barabe, eds., Symmetry in Plants, World Scientific, Studies in Math. Biology and Medicine, Vol. 4.

Crossrefs

Column k=10 of A144287.

Programs

  • Haskell
    a036299 n = a036299_list !! n
    a036299_list = map read rabbits :: [Integer] where
       rabbits = "1" : "10" : zipWith (++) (tail rabbits) rabbits
    -- Reinhard Zumkeller, Jul 06 2014
    
  • Mathematica
    nxt[{a_,b_}]:=FromDigits[Join[IntegerDigits[b],IntegerDigits[a]]]; Transpose[NestList[{Last[#],nxt[#]}&,{1,10},10]][[1]] (* Harvey P. Dale, Oct 16 2011 *)
  • Python
    def aupton(terms):
      alst = [1, 10]
      while len(alst) < terms: alst.append(int(str(alst[-1]) + str(alst[-2])))
      return alst[:terms]
    print(aupton(9)) # Michael S. Branicky, Jan 10 2021

Formula

a(n+1) = concatenation of a(n) and a(n-1).

A061107 a(0) = 0, a(1) = 1, a(n) is the concatenation of a(n-2) and a(n-1) for n > 1.

Original entry on oeis.org

0, 1, 10, 101, 10110, 10110101, 1011010110110, 101101011011010110101, 1011010110110101101011011010110110, 1011010110110101101011011010110110101101011011010110101
Offset: 0

Views

Author

Amarnath Murthy, Apr 20 2001

Keywords

Comments

Original name was: In the Fibonacci rabbit problem we start with an immature pair 'I' which matures after one season to 'M'. This mature pair after one season stays alive and breeds a new immature pair and we get the following sequence I, MI, MIM, MIMMI, MIMMIMIM, MIMMIMIMMIMMI... if we replace 'I' by a '0' and 'M' by a '1' we get the required binary sequence.

Examples

			a(0) = 0, a(1) = 1, a(2) = a(1)a(0)= 10, etc.
		

References

  • Amarnath Murthy, Smarandache Reverse auto correlated sequences and some Fibonacci derived sequences, Smarandache Notions Journal Vol. 12, No. 1-2-3, Spring 2001.
  • Ian Stewart, The Magical Maze.

Crossrefs

Cf. A063896, A131242. See A005203 for the sequence version converted to decimal.
Column k=10 of A144287.

Programs

  • Maple
    A[0]:= 0: A[1]:= 1: A[2]:= 10:
    for n from 3 to 20 do
    A[n]:= 10^(ilog10(A[n-2])+1)*A[n-1]+A[n-2]
    od:
    seq(A[n],n=0..10); # Robert Israel, Apr 30 2015
  • Mathematica
    nxt[{a_,b_}]:={b,FromDigits[Join[IntegerDigits[b],IntegerDigits[a]]]}; Transpose[NestList[nxt,{0,1},10]][[1]] (* Harvey P. Dale, Jul 05 2015 *)
  • PARI
    { default(realprecision, 100); L=log(10); for (n=0, 15, if (n>2, a=a1*10^(log(a2)\L + 1) + a2; a2=a1; a1=a, if (n==0, a=0, if (n==1, a=a2=1, a=a1=10))); write("b061107.txt", n, " ", a) ) } \\ Harry J. Smith, Jul 18 2009

Formula

a(0) = 0, a(1) =1, a(n) = concatenation of a(n-1) and a(n-2).
a(n) = a(n-1)*2^floor(log_2(a(n-2))+1)+a(n-2), for n>2, a(2)=10 (base 2). - Hieronymus Fischer, Jun 26 2007
a(n) = A036299(n-1), n>0. - R. J. Mathar, Oct 02 2008
a(n) can be transformed by a(n-1) when you change every single "1"(from a(n-1)) into "10" and every single "0"(from a(n-1)) into "1". [YuJiping and Sirius Caffrey, Apr 30 2015]

Extensions

More terms from Hieronymus Fischer, Jun 26 2007

A005205 Coding Fibonacci numbers.

Original entry on oeis.org

1, 3, 10, 93, 2521, 612696, 4019900977, 6409020585966267, 67040619014505181883304178, 1118048584563024433220786501983631190591549, 195042693446883195450571898296824337898272003171567594807867055549521
Offset: 1

Views

Author

Keywords

Comments

Binary Fibonacci (or rabbit) sequence A036299, read in base 3, then converted to decimal. - Jonathan Vos Post, Oct 19 2007

Examples

			a(0) = 1 because A036299(0) = "1" and 1 base 3 = 1 base 10.
a(1) = 3 because A036299(1) = "10" and 10 base 3 = 3 base 10.
a(2) = 10 because A036299(2) = "101" and 101 base 3 = 10 base 10.
a(3) = 93 because A036299(3) = "10110" and 10110 base 3 = 93 base 10.
a(4) = 2521 because A036299(4) = "10110101" and 10110101 base 3 = 2521 base 10.
a(5) = 612696 because A036299(5) = "1011010110110" and 1011010110110 base 3 = 612696 base 10.
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column k=3 of A144287.

Programs

  • Maple
    b:= proc(n) option remember; `if` (n<2, [n, n], [b(n-1)[1] *3^b(n-1)[2] +b(n-2)[1], b(n-1)[2] +b(n-2)[2]]) end: a:= n-> b(n)[1]: seq(a(n), n=1..11);  # Alois P. Heinz, Sep 17 2008
  • Mathematica
    b[0] = {1}; b[1] = {1, 0}; b[n_] := b[n] = Join[b[n-1], b[n-2]]; a[n_] := FromDigits[b[n], 3]; Table[a[n], {n, 0, 10}] (* Jean-François Alcover, Apr 24 2014 *)

Extensions

More terms from Jonathan Vos Post, Oct 19 2007
Corrected (a(4) was missing) and extended by Alois P. Heinz, Sep 17 2008

A320986 Fibonacci rabbit sequence number n coded in base four.

Original entry on oeis.org

0, 1, 4, 17, 276, 17681, 18105620, 1186569930001, 79629360058944734484, 350213629188686097286494407640337, 103364819020299355365011185381334444307580296786887956
Offset: 0

Views

Author

Alois P. Heinz, Oct 25 2018

Keywords

Crossrefs

Column k=4 of A144287.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<2, [n$2], [b(n-1)[1]*
          4^b(n-1)[2]+b(n-2)[1], b(n-1)[2]+b(n-2)[2]])
        end:
    a:= n-> b(n)[1]:
    seq(a(n), n=0..11);

A320987 Fibonacci rabbit sequence number n coded in base five.

Original entry on oeis.org

0, 1, 5, 26, 655, 81901, 255941280, 99977062581901, 122042312722047375081905, 58194309578918159047081570466564535026, 33873546390630164560327289199086683235486077084641297863363155
Offset: 0

Views

Author

Alois P. Heinz, Oct 25 2018

Keywords

Crossrefs

Column k=5 of A144287.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<2, [n$2], [b(n-1)[1]*
          5^b(n-1)[2]+b(n-2)[1], b(n-1)[2]+b(n-2)[2]])
        end:
    a:= n-> b(n)[1]:
    seq(a(n), n=0..11);

A320988 Fibonacci rabbit sequence number n coded in base six.

Original entry on oeis.org

0, 1, 6, 37, 1338, 289045, 2247615258, 3775130549469973, 49305824977081270580396826, 1081619448805341465793189347926225612555029, 309896735146874396575135322682564794037430646677718800894678718858010
Offset: 0

Views

Author

Alois P. Heinz, Oct 25 2018

Keywords

Crossrefs

Column k=6 of A144287.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<2, [n$2], [b(n-1)[1]*
          6^b(n-1)[2]+b(n-2)[1], b(n-1)[2]+b(n-2)[2]])
        end:
    a:= n-> b(n)[1]:
    seq(a(n), n=0..11);

A320989 Fibonacci rabbit sequence number n coded in base seven.

Original entry on oeis.org

0, 1, 7, 50, 2457, 842801, 14164958864, 81658169024988865, 7911779188478711198209076919, 4419091543264985265125879423229594334610523298, 239147782774557159658813554446871692442583155391399547503168277134702036921
Offset: 0

Views

Author

Alois P. Heinz, Oct 25 2018

Keywords

Crossrefs

Column k=7 of A144287.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<2, [n$2], [b(n-1)[1]*
          7^b(n-1)[2]+b(n-2)[1], b(n-1)[2]+b(n-2)[2]])
        end:
    a:= n-> b(n)[1]:
    seq(a(n), n=0..11);

A320990 Fibonacci rabbit sequence number n coded in base eight.

Original entry on oeis.org

0, 1, 8, 65, 4168, 2134081, 69929570376, 1173223506987487297, 644986443956439734064225751112, 5948949931338226254069168911286743617840154185793, 30164759804754346385078845671118798583946045417223576862481934288047850387443784
Offset: 0

Views

Author

Alois P. Heinz, Oct 25 2018

Keywords

Crossrefs

Column k=8 of A144287.

Programs

  • Maple
    b:= proc(n) option remember; `if`(n<2, [n$2], [b(n-1)[1]*
          8^b(n-1)[2]+b(n-2)[1], b(n-1)[2]+b(n-2)[2]])
        end:
    a:= n-> b(n)[1]:
    seq(a(n), n=0..11);
Showing 1-10 of 11 results. Next