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.

A110766 Fractalization of Pi.

Original entry on oeis.org

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

Views

Author

Alexandre Wajnberg, Sep 15 2005

Keywords

Comments

Self-descriptive sequence: even terms are the sequence itself, odd terms are the digits of the decimal expansion of Pi.

Crossrefs

Cf. A000796 (Pi), A003602.
Cf. A110779 (of e), A110812 (of sqrt 2), A382130 (of phi).

Programs

  • Haskell
    import Data.List (transpose)
    a110766 n = a110766_list !! (n-1)
    a110766_list = concat $ transpose [a000796_list, a110766_list]
    -- Reinhard Zumkeller, Aug 29 2014

Formula

a(2n) = a(n); a(2n-1) = digits of Pi.

Extensions

a(85) corrected and formula fixed by Reinhard Zumkeller, Aug 29 2014

A110812 Fractalization of sqrt 2.

Original entry on oeis.org

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

Views

Author

Alexandre Wajnberg, Sep 15 2005

Keywords

Comments

Self-descriptive sequence: even terms are the sequence itself, odd terms are the digits of the decimal expansion of sqrt 2.

Crossrefs

Cf. A002193 (sqrt 2), A003602.
Cf. A110766 (of Pi), A110779 (of e), A382130 (of phi).

Formula

a(2n)=a(n); a(2n+1)=digits of sqrt 2.

A110963 Fractalization of Kimberling's paraphrases sequence beginning with 1.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 1, 3, 2, 2, 1, 4, 1, 1, 1, 5, 3, 3, 2, 6, 2, 2, 1, 7, 4, 4, 1, 8, 1, 1, 1, 9, 5, 5, 3, 10, 3, 3, 2, 11, 6, 6, 2, 12, 2, 2, 1, 13, 7, 7, 4, 14, 4, 4, 1, 15, 8, 8, 1, 16, 1, 1, 1, 17, 9, 9, 5, 18, 5, 5, 3, 19, 10, 10, 3, 20, 3, 3, 2, 21, 11, 11, 6, 22, 6, 6, 2, 23, 12, 12, 2, 24, 2, 2, 1, 25, 13
Offset: 1

Views

Author

Alexandre Wajnberg, Sep 26 2005

Keywords

Comments

Self-descriptive sequence: terms at even indices are the sequence itself, terms at odd indices (the skeleton of this sequence) are the terms of Kimberling's paraphrases sequence (A003602) beginning with 1.

Crossrefs

One more than A110962 (but note the different starting offsets).
Cf. A353366 (Dirichlet inverse), A353367 (sum with it).

Programs

Formula

For even n, a(n) = a(n/2), for odd n, a(n) = A003602((1+n)/2). - Antti Karttunen, Apr 03 2022
For n >= 0, (Start)
a(4n+2) = a(4n+3) = A003602(1+n).
a(8n+1) = A005408(n) = 2*n + 1.
a(4n+1) = a(8n+2) = a(8n+3) = 1+n.
a(n) = A110962(n-1) + 1.
(End)
a(n) = A353367(4*n). - Antti Karttunen, Apr 20 2022
a(n) = A003602(A003602(n)). - Ridouane Oudra, Dec 28 2024

Extensions

Entry edited, starting offset corrected (from 0 to 1), and the offsets in formulas changed accordingly, and more terms added by Antti Karttunen, Apr 03 2022

A382130 Fractalization of the golden ratio.

Original entry on oeis.org

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

Views

Author

David Cleaver, Mar 16 2025

Keywords

Comments

Self-descriptive sequence: even indexed terms are the sequence itself, odd indexed terms are the decimal digits of the golden ratio.
This is an r1k1 fractal sequence, where r1k1 means: remove 1 term, keep 1 term, repeat. The Removed terms are the sequence that has been fractalized, and the Kept terms are the original fractal sequence.
This fractal sequence is not a Kimberling fractal sequence because if you delete the first occurrence of each term, the remaining sequence is not the same as the original.

Crossrefs

Bisection gives A001622 (odd part).

Formula

a(2n) = a(n); a(2n-1) = A001622(n), n >= 1.
a(n) = A001622(A003602(n)).

A110962 Fractalization of A025480, zero-based version of Kimberling's paraphrases sequence.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 0, 2, 1, 1, 0, 3, 0, 0, 0, 4, 2, 2, 1, 5, 1, 1, 0, 6, 3, 3, 0, 7, 0, 0, 0, 8, 4, 4, 2, 9, 2, 2, 1, 10, 5, 5, 1, 11, 1, 1, 0, 12, 6, 6, 3, 13, 3, 3, 0, 14, 7, 7, 0, 15, 0, 0, 0, 16, 8, 8, 4, 17, 4, 4, 2, 18, 9, 9, 2, 19, 2, 2, 1, 20, 10, 10, 5, 21, 5, 5, 1, 22, 11, 11, 1, 23, 1, 1, 0, 24, 12, 12
Offset: 0

Views

Author

Alexandre Wajnberg, Sep 26 2005

Keywords

Comments

Self-descriptive sequence: the terms at odd indices are the sequence itself, while the terms at even indices (the skeleton of this sequence) are the terms of A025480, which is a zero-based sequence of Kimberling's paraphrases sequence, A003602.

Crossrefs

One less than A110963 (note also the different starting offsets).

Programs

Formula

For even n, a(n) = A025480(n/2), for odd n, a(n) = a((n-1)/2). - Antti Karttunen, Apr 18 2022
a(2n+1) = a(4n+3) = a(n).
a(2n) = a(4n+1) = a(4n+2) = A025480(n/2).
a(4n) = a(8n+1) = a(8n+2) = n.
a(n) = A110963(1+n) - 1.

Extensions

Entry edited and more terms added by Antti Karttunen, Apr 18 2022

A382128 Fractalization of the Recamán sequence.

Original entry on oeis.org

0, 0, 1, 0, 3, 1, 6, 0, 2, 3, 7, 1, 13, 6, 20, 0, 12, 2, 21, 3, 11, 7, 22, 1, 10, 13, 23, 6, 9, 20, 24, 0, 8, 12, 25, 2, 43, 21, 62, 3, 42, 11, 63, 7, 41, 22, 18, 1, 42, 10, 17, 13, 43, 23, 16, 6, 44, 9, 15, 20, 45, 24, 14, 0, 46, 8, 79, 12, 113, 25, 78, 2, 114, 43, 77, 21, 39, 62, 78
Offset: 1

Views

Author

David Cleaver, Mar 16 2025

Keywords

Comments

Self-descriptive sequence: even indexed terms are the sequence itself, odd indexed terms are the Recamán sequence.
This is an r1k1 fractal sequence, where r1k1 means: remove 1 term, keep 1 term, repeat. The Removed terms are the sequence that has been fractalized, and the Kept terms are the original fractal sequence.
This fractal sequence is not a Kimberling fractal sequence because if you delete the first occurrence of each term, the remaining sequence is not the same as the original. This sequence fails to be a Kimberling fractal due to having consecutive terms that both appeared earlier in the sequence, starting with the 1 and 42 at index 48 and 49, respectively.

Crossrefs

Formula

a(2n) = a(n); a(2n-1) = A005132(n), n >= 1.
a(n) = A005132(A003602(n)).

A382129 Fractalization of the prime numbers.

Original entry on oeis.org

2, 2, 3, 2, 5, 3, 7, 2, 11, 5, 13, 3, 17, 7, 19, 2, 23, 11, 29, 5, 31, 13, 37, 3, 41, 17, 43, 7, 47, 19, 53, 2, 59, 23, 61, 11, 67, 29, 71, 5, 73, 31, 79, 13, 83, 37, 89, 3, 97, 41, 101, 17, 103, 43, 107, 7, 109, 47, 113, 19, 127, 53, 131, 2, 137, 59, 139, 23, 149, 61, 151, 11, 157
Offset: 1

Views

Author

David Cleaver, Mar 16 2025

Keywords

Comments

Self-descriptive sequence: even indexed terms are the sequence itself, odd indexed terms are the prime numbers.
This is an r1k1 fractal sequence, where r1k1 means: remove 1 term, keep 1 term, repeat. The Removed terms are the sequence that has been fractalized, and the Kept terms are the original fractal sequence.
This fractal sequence is also a Kimberling fractal sequence because if you delete the first occurrence of each term, the remaining sequence is the same as the original.

Crossrefs

Programs

  • Mathematica
    a[n_] := Prime[(n/2^IntegerExponent[n, 2] + 1)/2]; Array[a, 100] (* Amiram Eldar, Mar 21 2025 *)

Formula

a(2n) = a(n); a(2n-1) = A000040(n), n >= 1.
a(n) = A000040(A003602(n)).
Showing 1-7 of 7 results.