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 1-2 of 2 results.

A353336 Sum of A353420 and its Dirichlet inverse.

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 6, 0, 2, 0, 8, 12, 1, 0, 14, 0, 3, 16, 10, 0, 2, 9, 12, 28, 4, 0, 12, 0, 1, 20, 14, 24, 9, 0, 16, 24, 3, 0, 22, 0, 5, 66, 20, 0, 2, 16, 25, 28, 6, 0, 56, 30, 4, 32, 22, 0, 12, 0, 26, 100, 1, 36, 24, 0, 7, 40, 28, 0, 9, 0, 28, 86, 8, 40, 34, 0, 3, 157, 30, 0, 19, 42, 32, 44, 5, 0, 52, 48
Offset: 1

Views

Author

Antti Karttunen, Apr 20 2022

Keywords

Comments

The first negative term is a(255255) = -11936.

Crossrefs

Cf. A003961, A126760, A353420 (also a quadrisection of this sequence), A353335.
Cf. also A323882, A323894, A349135.

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); };
    A126760(n) = {n&&n\=3^valuation(n, 3)<A126760
    A353420(n) = A126760(A003961(n));
    v353335 = DirInverseCorrect(vector(up_to,n,A353420(n)));
    A353335(n) = v353335[n];
    A353336(n) = (A353420(n)+A353335(n));

Formula

a(n) = A353420(n) + A353335(n).
For n > 1, a(n) = -Sum_{d|n, 1A353420(d) * A353335(n/d).

A353335 Dirichlet inverse of A353420.

Original entry on oeis.org

1, -1, -2, 0, -3, 2, -4, 0, -5, 3, -5, 0, -6, 4, 0, 0, -7, 5, -8, 0, -3, 5, -10, 0, -8, 6, -14, 0, -11, 0, -13, 0, -2, 7, -2, 0, -14, 8, -5, 0, -15, 3, -16, 0, 7, 10, -18, 0, -25, 8, -4, 0, -20, 14, -1, 0, -7, 11, -21, 0, -23, 13, 8, 0, -4, 2, -24, 0, -9, 2, -25, 0, -27, 14, 4, 0, -8, 5, -28, 0, -52, 15, -30, 0, -3
Offset: 1

Views

Author

Antti Karttunen, Apr 20 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(dA003961(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
    A126760(n) = {n&&n\=3^valuation(n, 3)<A126760
    A353420(n) = A126760(A003961(n));
    v353335 = DirInverseCorrect(vector(up_to,n,A353420(n)));
    A353335(n) = v353335[n];

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A353420(n/d) * a(d).
a(n) = A353336(n) - A353420(n).
Showing 1-2 of 2 results.