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 1-6 of 6 results.

A214679 A(n,k) = Fibonacci(n) represented in bijective base-k numeration; square array A(n,k), n>=1, k>=1, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 11, 1, 1, 2, 111, 1, 1, 2, 11, 11111, 1, 1, 2, 3, 21, 11111111, 1, 1, 2, 3, 12, 112, 1111111111111, 1, 1, 2, 3, 11, 22, 221, 111111111111111111111, 1, 1, 2, 3, 5, 14, 111, 1221, 1111111111111111111111111111111111
Offset: 1

Views

Author

Alois P. Heinz, Jul 25 2012

Keywords

Comments

The digit set for bijective base-k numeration is {1, 2, ..., k}.

Examples

			Square array A(n,k) begins:
:                     1,    1,   1,   1,   1,  1,  1,  1,  1, ...
:                     1,    1,   1,   1,   1,  1,  1,  1,  1, ...
:                    11,    2,   2,   2,   2,  2,  2,  2,  2, ...
:                   111,   11,   3,   3,   3,  3,  3,  3,  3, ...
:                 11111,   21,  12,  11,   5,  5,  5,  5,  5, ...
:              11111111,  112,  22,  14,  13, 12, 11,  8,  8, ...
:         1111111111111,  221, 111,  31,  23, 21, 16, 15, 14, ...
: 111111111111111111111, 1221, 133, 111,  41, 33, 27, 25, 23, ...
		

Crossrefs

Programs

  • Maple
    with(combinat):
    A:= proc(n, b) local d, l, m; m:= fibonacci(n); l:= NULL;
          while m>0 do  d:= irem(m, b, 'm');
            if d=0 then d:=b; m:=m-1 fi;
            l:= d, l
          od; parse(cat(l))
        end:
    seq(seq(A(n, 1+d-n), n=1..d), d=1..10);
  • Mathematica
    A[n_, b_] := Module[{d, l, m}, m = Fibonacci@n; l = Nothing; While[m > 0, {m, d} = QuotientRemainder[m, b]; If[d == 0, d = b; m--]; l = {d, l}]; FromDigits @ Flatten @ l];
    Table[A[n, d-n+1], {d, 1, 10}, {n, 1, d}] // Flatten (* Jean-François Alcover, May 28 2019, from Maple *)

Formula

A(n,k) = A214676(A000045(n),k).

A131293 Concatenate a(n-2) and a(n-1) to get a(n); start with a(0)=0, a(1)=1, delete the leading zero. Also: concatenate Fibonacci(n) 1's.

Original entry on oeis.org

0, 1, 1, 11, 111, 11111, 11111111, 1111111111111, 111111111111111111111, 1111111111111111111111111111111111, 1111111111111111111111111111111111111111111111111111111
Offset: 0

Views

Author

Hieronymus Fischer, Jun 26 2007

Keywords

Comments

Interpreted as base-2 numbers the result is A063896.
This sequence differs from A108047 by the leading a(0) = 0. - Jason Kimberley, Dec 15 2012

Examples

			a(3)=11, a(4)=111, so a(5) = a(4)*a(3) = 11111.
		

Crossrefs

Programs

  • Haskell
    import Data.Function (on)
    a131293 n = a131293_list !! n
    a131293_list = 0 : 1 : map read
                   (zipWith ((++) `on` show) a131293_list $ tail a131293_list)
    -- Reinhard Zumkeller, Oct 05 2015
  • Magma
    [(10^Fibonacci(n)-1)/9: n in [0..10]]; // Vincenzo Librandi, Aug 29 2011
    
  • Maple
    a:= n-> parse(cat(0, 1$combinat[fibonacci](n))):
    seq(a(n), n=0..11);  # Alois P. Heinz, Apr 17 2020
  • Mathematica
    Join[{0},FromDigits/@(PadLeft[{},#,1]&/@Fibonacci[Range[10]])] (* Harvey P. Dale, Aug 28 2011 *)

Formula

a(n) = a(n-2)*10^ceiling(log_10(a(n-1))) + a(n-1) for n > 1.
a(n) = (10^Fibonacci(n) - 1)/9.

A037842 Fibonacci numbers in base 1.

Original entry on oeis.org

1, 11, 111, 11111, 11111111, 1111111111111, 111111111111111111111, 1111111111111111111111111111111111, 1111111111111111111111111111111111111111111111111111111
Offset: 0

Views

Author

N. J. A. Sloane, Feb 27 2000

Keywords

Crossrefs

Programs

  • Mathematica
    FromDigits[Table[1,{#}]]&/@Fibonacci[Range[2,10]] (* Harvey P. Dale, Apr 06 2013 *)

Formula

a(n+2) = concat( a(n+1), a(n) ), a(0) = 1, a(1) = 11. - corrected by Jason Kimberley, Dec 17 2012

Extensions

More terms from James Sellers, Mar 01 2000

A214326 Square array read by antidiagonals in which T(n,b) gives the n-th Fibonacci number written in base b with n,b >= 1.

Original entry on oeis.org

1, 1, 1, 1, 1, 11, 1, 1, 10, 111, 1, 1, 2, 11, 11111, 1, 1, 2, 10, 101, 11111111, 1, 1, 2, 3, 12, 1000, 1111111111111, 1, 1, 2, 3, 11, 22, 1101, 111111111111111111111, 1, 1, 2, 3, 10, 20, 111, 10101, 1111111111111111111111111111111111, 1, 1, 2, 3, 5, 13, 31, 210, 100010
Offset: 1

Views

Author

Alois P. Heinz, Jul 24 2012

Keywords

Comments

For b > 10, some terms cannot be properly notated using only decimal characters.

Examples

			Square array A(n,b) begins:
              1,    1,   1,  1,  1,  1,  1,  1,  1,  1,  1,  1, ...
              1,    1,   1,  1,  1,  1,  1,  1,  1,  1,  1,  1, ...
             11,   10,   2,  2,  2,  2,  2,  2,  2,  2,  2,  2, ...
            111,   11,  10,  3,  3,  3,  3,  3,  3,  3,  3,  3, ...
          11111,  101,  12, 11, 10,  5,  5,  5,  5,  5,  5,  5, ...
       11111111, 1000,  22, 20, 13, 12, 11, 10,  8,  8,  8,  8, ...
  1111111111111, 1101, 111, 31, 23, 21, 16, 15, 14, 13, 12, 11, ...
		

Crossrefs

Programs

  • Maple
    A:= proc(n, b) local f, l; f:= combinat[fibonacci](n);
          if b=1 then parse(cat(1$f))
        else l:= NULL;
             while f>0 do l:= irem(f, b, 'f'), l od;
             parse(cat(l))
          fi
        end:
    seq(seq(A(n, 1+d-n), n=1..d), d=1..10);

A121389 a(n) = 10^Fibonacci(n) - 1.

Original entry on oeis.org

0, 9, 9, 99, 999, 99999, 99999999, 9999999999999, 999999999999999999999, 9999999999999999999999999999999999, 9999999999999999999999999999999999999999999999999999999
Offset: 0

Views

Author

Rick L. Shepherd, Jul 26 2006

Keywords

Comments

Each a(n) has Fibonacci(n) (trailing) 9's. In general, if the same recurrence below is used with any a(0), a(1) >= 0, then, for all k >= 2, a(k) has the same number of trailing 9's as a(k-2) and a(k-1) have altogether (see for example A121390).

Crossrefs

Programs

  • Mathematica
    10^Fibonacci[Range[0,10]]-1 (* Harvey P. Dale, Dec 24 2022 *)

Formula

a(n) = 10^Fibonacci(n) - 1 = 10^A000045(n) - 1 (= 9*A108047(n) for n>=1). a(0) = 0; a(1) = 9; a(n) = a(n-2)*a(n-1) + a(n-2) + a(n-1).

A334025 a(0)=0, a(1)=1; and a(n) = {2*a(n-2), 2*a(n-1)}, where {x,y} is the concatenation of x and y.

Original entry on oeis.org

0, 1, 2, 24, 448, 48896, 89697792, 97792179395584, 179395584195584358791168, 195584358791168358791168391168717582336, 358791168391168717582336391168717582336717582336782337435164672
Offset: 0

Views

Author

Jamie Robert Creasey, Apr 14 2020

Keywords

Comments

This sequence, due to the process of concatenating one number with another, bears similarities to A131293 and other familiar sequences. However, unlike A131293, this sequence increases at a faster rate. It happens due to the multiplier applied to the existing terms, which increases the number of digits present in the successive term drastically (see a(7) and a(8)). a(11) is too large to include here and has 102 digits.

Examples

			a(2) = {2*a(2-2), 2*a(2-1)} = {2*0, 2*1} = 02 = 2.
a(5) = {2*a(5-2), 2*a(5-1)} = {2*24, 2*448} = 48896.
		

Crossrefs

Programs

  • Mathematica
    a[0] = 0; a[1] = 1; a[n_] := a[n] = FromDigits @ Join[IntegerDigits[2*a[n - 2]], IntegerDigits[2*a[n - 1]]]; Array[a, 11, 0] (* Amiram Eldar, Apr 18 2020 *)
Showing 1-6 of 6 results.