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 1-3 of 3 results.

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

A353367 Sum of A110963 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 1, 0, 2, 0, 1, 1, 4, 0, 1, 0, 2, 4, 1, 0, 5, 0, 2, 2, 4, 0, 1, 4, 8, 5, 1, 0, -2, 0, 1, 4, 10, 4, 3, 0, 6, 8, 2, 0, 10, 0, 2, 8, 4, 0, 1, 1, 10, 10, 4, 0, 3, 8, 1, 6, 16, 0, 1, 0, 2, 15, 1, 16, 14, 0, 5, 4, 6, 0, 3, 0, 20, 6, 3, 4, -2, 0, 2, 9, 22, 0, 6, 20, 12, 16, 2, 0, 16, 8, 2, 2, 4, 12, 1, 0, 25, 24
Offset: 1

Views

Author

Antti Karttunen, Apr 18 2022

Keywords

Comments

Note the negative terms, in contrast to A349135, which apparently has none.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA003602(n) = (1+(n>>valuation(n,2)))/2;
    A110963(n) = if(n%2, A003602((1+n)/2), A110963(n/2));
    v353366 = DirInverseCorrect(vector(up_to,n,A110963(n)));
    A353366(n) = v353366[n];
    A353367(n) = (A110963(n)+A353366(n));

Formula

a(n) = A110963(n) + A353366(n).
For n > 1, a(n) = -Sum_{d|n, 1A110963(d) * A353366(n/d).
For all n >= 1, a(4*n) = A110963(n), and a(8*n-4) = A003602(n).

A353368 Dirichlet inverse of A103391, "even fractal sequence".

Original entry on oeis.org

1, -2, -2, 1, -2, 4, -3, -1, 2, 2, -4, -3, -3, 4, 3, 0, -2, -10, -6, 1, 8, 4, -7, 3, 1, -2, -8, -1, -5, -4, -9, -1, 14, -10, 2, 17, -6, 4, 1, -1, -4, -22, -12, 1, -3, 4, -13, -1, 6, -14, -6, 11, -8, 28, 1, 1, 19, -10, -16, 3, -9, 4, -25, -1, 10, -42, -18, 25, 18, 0, -19, -17, -6, -14, -12, 5, 13, 12, -21, 3, 24
Offset: 1

Views

Author

Antti Karttunen, Apr 18 2022

Keywords

Crossrefs

Programs

  • PARI
    up_to = 65537;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA003602(n) = (n/2^valuation(n, 2)+1)/2; \\ From A003602
    A103391(n) = if(1==n,1,(1+A003602(n-1)));
    v353368 = DirInverseCorrect(vector(up_to,n,A103391(n)));
    A353368(n) = v353368[n];

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A103391(n/d) * a(d).
a(n) = A353369(n) - A103391(n).
Showing 1-3 of 3 results.