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 10 results.

A245219 Continued fraction expansion of the constant c in A245218; c = sup{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A001951, else f(n,x) = 1/x.

Original entry on oeis.org

3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2, 2, 3, 2, 3, 2
Offset: 0

Views

Author

Clark Kimberling, Jul 13 2014

Keywords

Comments

See Comments at A245215.
Likely a duplicate of A097509. - R. J. Mathar, Jul 21 2014
Theorem: Referring to Problem B6 in the 81st William Lowell Putnam Mathematical Competition (see link), in the notation of the first solution, the sequence {c_i} equals A245219. This proves the conjecture in the previous comment. - Manjul Bhargava, Kiran Kedlaya, and Lenny Ng, Sep 09 2021.

Examples

			c = 3.43648484... ; the first 12 numbers f(n,1) comprise S(12) = {1, 2, 3, 1/3, 4/3, 7/3, 3/7, 10/7, 17/7, 24/7, 7/24, 31/24}; max(S(12)) = 24/7, with continued fraction [3,2,3].
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245217, A245218 (decimal expansion), A245222, A245225.
The following sequences are all essentially the same, in the sense that they are simple transformations of each other, with A003151 as the parent: A003151, A001951, A001952, A003152, A006337, A080763, A082844 (conjectured), A097509, A159684, A188037, A245219 (conjectured), A276862. - N. J. A. Sloane, Mar 09 2021

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = Sqrt[2]; w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; max = Max[N[Table[s[n], {n, 1, 3000}], 200]] (* A245217 *)
    ContinuedFraction[max, 120] (* A245219 *)

Extensions

Offset changed by Andrew Howroyd, Jul 07 2024

A245217 Decimal expansion of inf{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A001951, else f(n,x) = 1/x.

Original entry on oeis.org

2, 9, 0, 9, 9, 5, 0, 2, 7, 0, 8, 6, 5, 9, 0, 6, 3, 0, 7, 4, 0, 5, 1, 1, 6, 6, 8, 1, 8, 3, 7, 7, 7, 6, 5, 1, 3, 8, 5, 4, 3, 2, 0, 1, 6, 1, 0, 9, 6, 3, 8, 8, 9, 9, 6, 6, 2, 3, 6, 0, 5, 9, 9, 9, 3, 0, 5, 6, 4, 4, 0, 8, 2, 9, 8, 2, 1, 1, 8, 9, 6, 3, 0, 3, 3, 1
Offset: 1

Views

Author

Clark Kimberling, Jul 13 2014

Keywords

Comments

See Comments at A245215.

Examples

			c = 0.29099502708659063074051166818377765138543201...  The first 12 numbers f(n,1) comprise S(12) = {1, 2, 3, 1/3, 4/3, 7/3, 3/7, 10/7, 17/7, 24/7, 7/24, 31/24}; min(S(12)) = 7/24 = 0.29166...
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245215, A245218, A245220, A245223.

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = Sqrt[2]; w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; $RecursionLimit = tmpRec;
    m = Min[N[Table[s[n], {n, 1, 4000}], 300]]
    t = RealDigits[m]  (* A245217 *)
    (* Peter J. C. Moses, Jul 04 2014 *)

Formula

a(n)*sup{f(n,1)} = 1.

A245222 Continued fraction expansion of the constant c in A245221; c = sup{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A022838, else f(n,x) = 1/x.

Original entry on oeis.org

2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1
Offset: 0

Views

Author

Clark Kimberling, Jul 14 2014

Keywords

Comments

See Comments at A245215.
Appears to be the same as the sequence 1 + [x == 0 (mod sqrt(3))], as x runs over the elements of N U N*sqrt(3) in increasing order, where N = {0, 1, 2, 3, ...} and [...] is the Iverson bracket. - M. F. Hasler, Feb 06 2025

Examples

			c = 2.7207664507294752975469517348171513242... ; the first 12 numbers f(n,1) comprise S(12) = {1, 2, 1/2, 3/2, 2/3, 5/3, 8/3, 3/8, 11/8, 8/11, 19/11, 11/19}; max(S(12)) = 8/3, with continued fraction [2,1,2].
From _M. F. Hasler_, Feb 06 2025: (Start)
Illustration of the "multiple of sqrt(3)" comment:
  n:  0   1   2    3   4    5    6   7   8    9   10  11  12   13  14  15
  x:  0   1  1.73  2   3   3.46  4   5  5.20  6  6.93  7   8  8.66  9  10
  m:  1   0   1    0   0    1    0   0   1    0   1    0   0   1    0   0
Here, x lists the elements of N U N*sqrt(3), and m = 1 if x == 0 (mod sqrt(3)), i.e., x is an integer multiple of sqrt(3). The sequence a(n) is m + 1. (End)
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245217, A245219, A245220, A245221 (decimal expansion).
Cf. A144612 (Sturmian word of slope (3-sqrt(3))/2; same as 2-a(n)).
Cf. A006337 (Hofstadter's eta sequence: an analog with sqrt(2)).

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = Sqrt[3]; w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; max = Max[N[Table[s[n], {n, 1, 3000}], 200]] (* A245221 *)
    ContinuedFraction[max, 120] (* A245222 *)
  • PARI
    /* illustration of the comment related to sqrt(3)*/
    [1+(abs(x-x\/s*s)<1e-9) | x<-Set(concat(Col([1.,s=sqrt(3)]~*[0..99])))[1..99] ] \\ M. F. Hasler, Feb 06 2025

Formula

a(n) = 2 - A144612(n) for all n > 0. - M. F. Hasler, Feb 06 2025

Extensions

Offset changed by Andrew Howroyd, Aug 08 2024

A245220 Decimal expansion of inf{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A022838, else f(n,x) = 1/x.

Original entry on oeis.org

3, 6, 7, 5, 4, 3, 4, 9, 1, 1, 8, 4, 9, 5, 1, 2, 4, 8, 7, 2, 1, 2, 6, 0, 9, 7, 2, 5, 4, 1, 0, 9, 2, 5, 4, 0, 7, 0, 8, 3, 4, 4, 0, 8, 8, 6, 0, 5, 2, 0, 6, 3, 6, 5, 9, 3, 6, 0, 9, 1, 7, 8, 7, 0, 4, 6, 9, 2, 5, 9, 5, 1, 9, 7, 4, 4, 3, 5, 6, 0, 6, 2, 5, 8, 0, 2
Offset: 1

Views

Author

Clark Kimberling, Jul 14 2014

Keywords

Comments

See Comments at A245215.

Examples

			c = 0.367543491184951248721260972541092540...  The first 12 numbers f(n,1) comprise S(12) = {1, 2, 1/2, 3/2, 2/3, 5/3, 8/3, 3/8, 11/8, 8/11, 19/11, 11/19}; min(S(12)) = 3/8 = 0.375... and max(S(12)) = 8/3 = 2.666...
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245215, A245217, A245221, A245222.

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = Sqrt[3]; w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; $RecursionLimit = tmpRec;
    m = Min[N[Table[s[n], {n, 1, 4000}], 300]]
    t = RealDigits[m]  (* A245220 *)
    (* Peter J. C. Moses, Jul 04 2014 *)

Formula

a(n)*sup{f(n,1)} = 1.

A245223 Decimal expansion of inf{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A054385, else f(n,x) = 1/x.

Original entry on oeis.org

3, 6, 9, 3, 0, 6, 3, 9, 6, 4, 5, 3, 0, 1, 2, 3, 0, 5, 9, 7, 2, 7, 8, 1, 6, 9, 3, 6, 8, 7, 1, 9, 0, 6, 6, 9, 4, 4, 5, 6, 3, 1, 3, 3, 1, 6, 9, 0, 3, 8, 4, 9, 6, 0, 5, 3, 1, 0, 9, 1, 0, 0, 2, 8, 8, 6, 3, 3, 4, 6, 9, 2, 4, 5, 3, 0, 2, 7, 0, 1, 2, 6, 2, 9, 8, 0
Offset: 1

Views

Author

Clark Kimberling, Jul 14 2014

Keywords

Comments

See Comments at A245215.

Examples

			c = 0.36930639645301230597278169368719066944...  The first 16 numbers f(n,1) comprise S(16) = {1, 2, 1/2, 3/2, 5/2, 2/5, 7/5, 12/5, 5/12, 17/12, 12/17, 29/17}; min(S(16)) = 17/46 = 0.36956... and max(S(12)) = 46/17 = 2.7058...
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245215, A245217, A245220, A245224.

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = E/(E-1); w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; $RecursionLimit = tmpRec;
    m = Min[N[Table[s[n], {n, 1, 4000}], 300]]
    RealDigits[m]  (* A245223 *)
    (* Peter J. C. Moses, Jul 04 2014 *)

Formula

a(n)*sup{f(n,1)} = 1.

A245218 Decimal expansion of sup{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A001951, else f(n,x) = 1/x.

Original entry on oeis.org

3, 4, 3, 6, 4, 8, 4, 8, 4, 3, 0, 9, 8, 1, 3, 5, 1, 7, 8, 4, 6, 1, 0, 5, 3, 9, 0, 3, 9, 2, 4, 7, 1, 3, 5, 6, 5, 0, 0, 9, 8, 8, 1, 6, 0, 6, 7, 3, 7, 8, 3, 0, 5, 4, 3, 6, 5, 8, 6, 6, 6, 6, 0, 5, 1, 7, 6, 2, 7, 1, 0, 7, 9, 0, 7, 6, 9, 8, 6, 2, 6, 0, 4, 6, 1, 6
Offset: 1

Views

Author

Clark Kimberling, Jul 13 2014

Keywords

Comments

See Comments at A245215.

Examples

			c = 3.43648484309813517846105390392471356500...  The first 12 numbers f(n,1) comprise S(12) = {1, 2, 3, 1/3, 4/3, 7/3, 3/7, 10/7, 17/7, 24/7, 7/24, 31/24}; max(S(12)) = 24/7 = 3.42857...
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245215, A245217, A245219, A245223.

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = Sqrt[2]; w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; $RecursionLimit = tmpRec;
    m = Max[N[Table[s[n], {n, 1, 4000}], 300]]
    t = RealDigits[m]  (* A245217 *)
    (* Peter J. C. Moses, Jul 04 2014 *)

Formula

a(n)*inf{f(n,1)} = 1.

A245221 Decimal expansion of sup{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A022838, else f(n,x) = 1/x.

Original entry on oeis.org

2, 7, 2, 0, 7, 6, 6, 4, 5, 0, 7, 2, 9, 4, 7, 5, 2, 9, 7, 5, 4, 6, 9, 5, 1, 7, 3, 4, 8, 1, 7, 1, 5, 1, 3, 2, 4, 2, 5, 4, 7, 4, 9, 7, 9, 6, 1, 7, 1, 4, 6, 4, 1, 6, 7, 9, 0, 0, 0, 8, 2, 8, 3, 6, 6, 8, 7, 6, 6, 2, 4, 2, 1, 2, 1, 6, 7, 7, 7, 9, 0, 9, 7, 7, 8, 6
Offset: 1

Views

Author

Clark Kimberling, Jul 14 2014

Keywords

Comments

See Comments at A245215.

Examples

			c = 0.367543491184951248721260972541092540...  The first 12 numbers f(n,1) comprise S(12) = {1, 2, 1/2, 3/2, 2/3, 5/3, 8/3, 3/8, 11/8, 8/11, 19/11, 11/19}; min(S(12)) = 3/8 = 0.375... and max(S(12)) = 8/3 = 2.666...
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245215, A245217, A245220, A245222.

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = Sqrt[3]; w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; $RecursionLimit = tmpRec;
    m = Max[N[Table[s[n], {n, 1, 4000}], 300]]
    t = RealDigits[m]  (* A245221 *)
    (* Peter J. C. Moses, Jul 04 2014 *)

Formula

a(n)*inf{f(n,1)} = 1.

A245224 Decimal expansion of sup{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A054385, else f(n,x) = 1/x.

Original entry on oeis.org

2, 7, 0, 7, 7, 7, 8, 7, 1, 6, 0, 0, 5, 0, 7, 8, 1, 2, 4, 3, 4, 0, 2, 0, 6, 6, 6, 5, 9, 6, 3, 1, 3, 1, 6, 2, 9, 9, 2, 3, 3, 1, 2, 4, 2, 4, 9, 1, 0, 4, 4, 5, 1, 7, 6, 6, 6, 9, 1, 3, 7, 9, 1, 8, 3, 4, 6, 4, 8, 3, 0, 8, 8, 4, 3, 2, 3, 4, 7, 0, 0, 2, 3, 5, 5, 3
Offset: 1

Views

Author

Clark Kimberling, Jul 14 2014

Keywords

Comments

See Comments at A245215.

Examples

			c = 2.7077787160050781243402066659631316299233...  The first 16 numbers f(n,1) comprise S(16) = {1, 2, 1/2, 3/2, 5/2, 2/5, 7/5, 12/5, 5/12, 17/12, 12/17, 29/17}; min(S(16)) = 17/46 = 0.36956... and max(S(12)) = 46/17 = 2.7058...
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245215, A245217, A245220, A245224.

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = E/(E-1); w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; $RecursionLimit = tmpRec;
    m = Max[N[Table[s[n], {n, 1, 4000}], 300]]
    RealDigits[m]  (* A245224 *)
    (* Peter J. C. Moses, Jul 04 2014 *)

Formula

a(n)*inf{f(n,1)} = 1.

A245216 Decimal expansion of sup{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A000201, else f(n,x) = 1/x.

Original entry on oeis.org

2, 7, 2, 9, 9, 6, 7, 7, 4, 1, 5, 9, 9, 8, 0, 2, 4, 8, 7, 8, 9, 1, 6, 4, 6, 7, 7, 4, 8, 7, 5, 9, 0, 7, 5, 2, 1, 1, 4, 3, 7, 8, 4, 1, 1, 3, 5, 3, 7, 0, 3, 4, 6, 2, 5, 9, 8, 6, 9, 5, 2, 7, 2, 4, 5, 2, 9, 0, 0, 6, 8, 8, 6, 4, 9, 3, 2, 6, 4, 2, 8, 6, 8, 0, 0, 6
Offset: 1

Views

Author

Clark Kimberling, Jul 13 2014

Keywords

Comments

Equivalently, f(n,x) = 1/(f(n-1,x) if n is in A001950 (upper Wythoff sequence, given by w(n) = floor[tau*n], where tau = (1 + sqrt(5))/2, the golden ratio) and f(n,x) = f(n-1) + 1 otherwise. Let c = sup{f(n,1)}. The continued fraction of c is [2, 1, 2, 1, 2, 2, 1, 2, 2, 1, 2, ...], which appears to be identical to the Hofstadter eta-sequence at A006340. See Comments at A245215.

Examples

			c = 2.7299677415998024878916467748759075211...  The first 12 numbers f(n,1) comprise S(12) = {1, 2, 1/2, 3/2, 5/2, 2/5, 7/5, 5/7, 12/7, 19/7, 7/19, 26/19}; max(S(12)) = 19/7 = 2.71429...
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A006340, A245215, A245217, A245220, A245223.

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = GoldenRatio; w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; $RecursionLimit = tmpRec;
    m = Max[N[Table[s[n], {n, 1, 4000}], 300]]
    RealDigits[m]  (* A245216 *)
    (* Peter J. C. Moses, Jul 04 2014 *)

Formula

inf{f(n,1)}*(2 + a(n)) = 1.

A245225 Continued fraction expansion of the constant c in A245224; c = sup{f(n,1)}, where f(1,x) = x + 1 and thereafter f(n,x) = x + 1 if n is in A054385, else f(n,x) = 1/x.

Original entry on oeis.org

2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 1, 2, 2
Offset: 0

Views

Author

Clark Kimberling, Jul 14 2014

Keywords

Comments

See Comments at A245215.

Examples

			c = 2.70777871600507812434020666596313162... ; The first 16 numbers f(n,1) comprise S(16) = {1, 2, 1/2, 3/2, 5/2, 2/5, 7/5, 12/5, 5/12, 17/12, 12/17, 29/17}; max(S(16)) = 46/17, with continued fraction [2, 1, 2, 2, 2].
		

Crossrefs

Cf. A226080 (infinite Fibonacci tree), A245217, A245219, A245222, A245224 (decimal expansion).

Programs

  • Mathematica
    tmpRec = $RecursionLimit; $RecursionLimit = Infinity; u[x_] := u[x] = x + 1; d[x_] := d[x] = 1/x; r = E/(E-1); w = Table[Floor[k*r], {k, 2000}]; s[1] = 1; s[n_] := s[n] = If[MemberQ[w, n - 1], u[s[n - 1]], d[s[n - 1]]]; max = Max[N[Table[s[n], {n, 1, 3000}], 200]] (* A245224 *)
    ContinuedFraction[max, 120] (* A245225 *)

Extensions

Offset changed by Andrew Howroyd, Jul 07 2024
Showing 1-10 of 10 results.