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.

A349431 Dirichlet convolution of A003602 (Kimberling's paraphrases) with A055615 (Dirichlet inverse of n).

Original entry on oeis.org

1, -1, -1, -1, -2, 1, -3, -1, -1, 2, -5, 1, -6, 3, 4, -1, -8, 1, -9, 2, 6, 5, -11, 1, -2, 6, -1, 3, -14, -4, -15, -1, 10, 8, 12, 1, -18, 9, 12, 2, -20, -6, -21, 5, 4, 11, -23, 1, -3, 2, 16, 6, -26, 1, 20, 3, 18, 14, -29, -4, -30, 15, 6, -1, 24, -10, -33, 8, 22, -12, -35, 1, -36, 18, 4, 9, 30, -12, -39, 2, -1, 20
Offset: 1

Views

Author

Antti Karttunen, Nov 17 2021

Keywords

Comments

Dirichlet convolution of this sequence with A000010 gives A349136, which also proves the formula involving A023900.
Convolution with A000203 gives A349371.

Crossrefs

Sequence A297381 negated.
Cf. A003602, A023900, A055615, A297381, A349432 (Dirichlet inverse), A349433 (sum with it).
Cf. also A000010, A000203, A349136, A349371, and also A349444, A349447.

Programs

  • Mathematica
    k[n_] := (n / 2^IntegerExponent[n, 2] + 1)/2; a[n_] := DivisorSum[n, # * MoebiusMu [#] * k[n/#] &]; Array[a, 100] (* Amiram Eldar, Nov 18 2021 *)
  • PARI
    A003602(n) = (1+(n>>valuation(n,2)))/2;
    A055615(n) = (n*moebius(n));
    A349431(n) = sumdiv(n,d,A003602(n/d)*A055615(d));
    
  • PARI
    A023900(n) = factorback(apply(p -> 1-p, factor(n)[, 1]));
    A349431(n) = if(!bitand(n,n-1),A023900(n),A023900(n)/2);

Formula

a(n) = Sum_{d|n} A003602(n/d) * A055615(d).
a(n) = A023900(n) when n is a power of 2, and a(n) = A023900(n)/2 for all other numbers.
a(n) = -A297381(n).

A349432 Dirichlet convolution of A000027 (the identity function) with A349134 (Dirichlet inverse of Kimberling's paraphrases).

Original entry on oeis.org

1, 1, 1, 2, 2, 1, 3, 4, 2, 2, 5, 2, 6, 3, 0, 8, 8, 2, 9, 4, 0, 5, 11, 4, 6, 6, 4, 6, 14, 0, 15, 16, 0, 8, 0, 4, 18, 9, 0, 8, 20, 0, 21, 10, -2, 11, 23, 8, 12, 6, 0, 12, 26, 4, 0, 12, 0, 14, 29, 0, 30, 15, -3, 32, 0, 0, 33, 16, 0, 0, 35, 8, 36, 18, -4, 18, 0, 0, 39, 16, 8, 20, 41, 0, 0, 21, 0, 20, 44, -2, 0, 22, 0, 23
Offset: 1

Views

Author

Antti Karttunen, Nov 17 2021

Keywords

Crossrefs

Cf. A003602, A055615, A349134, A349431 (Dirichlet inverse), A349433 (sum with it).
Cf. also A349445, A349448.

Programs

  • Mathematica
    k[n_] := (n / 2^IntegerExponent[n, 2] + 1)/2; kinv[1] = 1; kinv[n_] := kinv[n] = -DivisorSum[n, kinv[#] * k[n/#] &, # < n &]; a[n_] := DivisorSum[n, # * kinv[n/#] &]; Array[a, 100] (* Amiram Eldar, Nov 18 2021 *)
  • 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(dA003602(n) = (1+(n>>valuation(n,2)))/2;
    v349134 = DirInverseCorrect(vector(up_to,n,A003602(n)));
    A349134(n) = v349134[n];
    A003602(n) = (1+(n>>valuation(n,2)))/2;
    A055615(n) = (n*moebius(n));
    A349432(n) = sumdiv(n,d,d*A349134(n/d));

A349446 a(n) = A349444(n) + A349445(n).

Original entry on oeis.org

2, 0, 0, 1, 0, -2, 0, 1, 1, -4, 0, -1, 0, -6, 4, 1, 0, -5, 0, -2, 6, -10, 0, -1, 4, -12, 5, -3, 0, -4, 0, 1, 10, -16, 12, -2, 0, -18, 12, -2, 0, -6, 0, -5, 14, -22, 0, -1, 9, -16, 16, -6, 0, -13, 20, -3, 18, -28, 0, 0, 0, -30, 21, 1, 24, -10, 0, -8, 22, -12, 0, -2, 0, -36, 24, -9, 30, -12, 0, -2, 19, -40, 0, 0, 32
Offset: 1

Views

Author

Antti Karttunen, Nov 18 2021

Keywords

Crossrefs

Cf. also A349433.

Programs

  • Mathematica
    s[n_] := MoebiusMu[n] - If[OddQ[n], 0, MoebiusMu[n/2]]; k[n_] := (n / 2^IntegerExponent[n, 2] + 1)/2; k[n_] := (n / 2^IntegerExponent[n, 2] + 1)/2; kinv[1] = 1; kinv[n_] := kinv[n] = -DivisorSum[n, kinv[#]*k[n/#] &, # < n &]; a[n_] := DivisorSum[n,  s[#]*k[n/#] + IntegerExponent[2*#, 2]*kinv[n/#] &]; Array[a, 100] (* Amiram Eldar, Nov 19 2021 *)
  • PARI
    A349446(n) = (A349444(n)+A349445(n)); \\ Needs also code from A349444 and A349445.

Formula

a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A349444(d) * A349445(n/d). [As the sequences are Dirichlet inverses of each other]
Showing 1-3 of 3 results.