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 1-5 of 5 results.

A323365 Sum of Stern's Diatomic sequence, A002487 and its Dirichlet inverse, A317843.

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 6, 0, 2, 0, 6, 12, 1, 0, 4, 0, 3, 12, 10, 0, 2, 9, 10, 8, 3, 0, -4, 0, 1, 20, 10, 18, 4, 0, 14, 20, 3, 0, 4, 0, 5, 4, 14, 0, 2, 9, 5, 20, 5, 0, 8, 30, 3, 28, 14, 0, 4, 0, 10, 20, 1, 30, -8, 0, 5, 28, 0, 0, 4, 0, 22, -2, 7, 30, 0, 0, 3, 16, 22, 0, 8, 30, 26, 28, 5, 0, 20, 30, 7, 20, 18, 42, 2, 0, 9, 4, 7, 0, 4, 0, 5, 0
Offset: 1

Views

Author

Antti Karttunen, Jan 13 2019

Keywords

Crossrefs

Cf. A002487 (also a quadrisection of this sequence), A317843.

Programs

Formula

a(n) = A002487(n) + A317843(n).
From Antti Karttunen, Dec 08 2021: (Start)
a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A002487(d) * A317843(n/d).
a(4*n) = A002487(n).
(End)

A323894 Sum of A048673 and its Dirichlet inverse, A323893.

Original entry on oeis.org

2, 0, 0, 4, 0, 12, 0, 12, 9, 16, 0, 26, 0, 24, 24, 37, 0, 46, 0, 36, 36, 28, 0, 76, 16, 36, 51, 56, 0, 58, 0, 114, 42, 40, 48, 121, 0, 48, 54, 106, 0, 94, 0, 66, 104, 60, 0, 223, 36, 92, 60, 86, 0, 220, 56, 166, 72, 64, 0, 164, 0, 76, 162, 349, 72, 112, 0, 96, 90, 136, 0, 354, 0, 84, 150, 116, 84, 148, 0, 312, 277, 88, 0, 260, 80, 96, 96
Offset: 1

Views

Author

Antti Karttunen, Feb 08 2019

Keywords

Comments

The first four negative terms are a(3063060) = -14126242, a(3423420) = -17546656, a(4084080) = -14460312, a(4144140) = -22677277. - Antti Karttunen, Apr 20 2022

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(dA003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961
    A048673(n) = (A003961(n)+1)/2;
    v323893 = DirInverse(vector(up_to,n,A048673(n)));
    A323893(n) = v323893[n];
    A323894(n) = (A048673(n)+A323893(n));

Formula

a(n) = A048673(n) + A323893(n).
For n > 1, a(n) = -Sum_{d|n, 1A048673(n/d) * A323893(d). - Antti Karttunen, Apr 20 2022
a(n) = A349135(A003961(n)). - Antti Karttunen, Nov 30 2024

A323885 Sum of A001511 and its Dirichlet inverse.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Feb 08 2019

Keywords

Crossrefs

Programs

  • PARI
    A001511(n) = (1+valuation(n,2));
    A092673(n) = (moebius(n)-if(n%2,0,moebius(n/2)));
    A323885(n) = (A001511(n)+A092673(n));
    
  • Python
    from sympy import mobius
    def A323885(n): return (n&-n).bit_length()+mobius(n)-(0 if n&1 else mobius(n>>1)) # Chai Wah Wu, Jul 13 2022

Formula

a(n) = A001511(n) + A092673(n).

A323887 Sum of Per Nørgård's "infinity sequence" (A004718) and its Dirichlet inverse (A323886).

Original entry on oeis.org

2, 0, 0, 1, 0, -4, 0, -1, 4, 0, 0, 2, 0, -6, 0, 1, 0, 0, 0, 0, 12, -2, 0, -2, 0, 2, 0, 3, 0, -8, 0, -1, 4, 0, 0, 2, 0, -6, -4, 0, 0, 10, 0, 1, 16, -4, 0, 2, 9, -6, 0, -1, 0, 0, 0, -3, 12, 4, 0, 4, 0, -10, -20, 1, 0, 0, 0, 0, 8, -2, 0, -2, 0, 2, 12, 3, 6, -12, 0, 0, -4, -2, 0, 1, 0, -4, -8, -1, 0, 16, -6, 2, 20, -6, 0, -2, 0, 11, 0, 3, 0, -8, 0, 1, 28
Offset: 1

Views

Author

Antti Karttunen, Feb 08 2019

Keywords

Comments

The composer Per Nørgård's name is also written in the OEIS as Per Noergaard.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    A004718list(up_to) = { my(v=vector(up_to)); v[1]=1; v[2]=-1; for(n=3, up_to, v[n] = if(n%2, 1+v[n>>1], -v[n/2])); (v); }; \\ After code in A004718.
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA004718list(up_to);
    A004718(n) = v004718[n];
    v323886 = DirInverse(v004718);
    A323886(n) = v323886[n];
    A323887(n) = (A004718(n)+A323886(n));

Formula

a(n) = A004718(n) + A323886(n).

A323895 Dirichlet inverse of binary Gray code, A003188.

Original entry on oeis.org

1, -3, -2, 3, -7, 7, -4, -3, -9, 27, -14, -10, -11, 15, 20, 3, -25, 35, -26, -45, -15, 55, -28, 13, 28, 43, 22, -24, -19, -91, -16, -3, 7, 99, 6, -58, -55, 103, -8, 63, -61, 55, -62, -94, 71, 111, -56, -16, -25, -148, 58, -73, -47, -107, 152, 33, 67, 75, -38, 196, -35, 63, 148, 3, 57, -53, -98, -171, 9, -59, -100, 78, -109, 219, -208, -178, 5, 13
Offset: 1

Views

Author

Antti Karttunen, Feb 08 2019

Keywords

Crossrefs

Programs

  • PARI
    up_to = 16384;
    DirInverseCorrect(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = (-u[1]*sumdiv(n, d, if(dA003188(n) = bitxor(n, n>>1);
    v323895 = DirInverseCorrect(vector(up_to,n,A003188(n)));
    A323895(n) = v323895[n];
Showing 1-5 of 5 results.