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 1-6 of 6 results.

A340197 a(1) = 1; for n > 1, a(n) = Sum_{d|n, dA318833(n/d)-1) * A340197(d).

Original entry on oeis.org

1, 0, 0, 2, 0, 7, 0, 6, 6, 13, 0, 13, 0, 19, 22, 18, 0, 19, 0, 23, 32, 31, 0, 53, 20, 37, 24, 33, 0, 21, 0, 54, 52, 49, 58, 110, 0, 55, 62, 95, 0, 29, 0, 53, 52, 67, 0, 185, 42, 53, 82, 63, 0, 139, 94, 137, 92, 85, 0, 321, 0, 91, 74, 162, 112, 45, 0, 83, 112, 45, 0, 403, 0, 109, 82, 93, 136, 53, 0, 331, 114, 121
Offset: 1

Views

Author

Antti Karttunen, Jan 05 2021

Keywords

Comments

See comments and question in A340140.

Crossrefs

Programs

Formula

a(1) = 1; for n > 1, a(n) = Sum_{d|n, dA318833(n/d)-1) * A340197(d).

A340367 Dirichlet inverse of sequence b(n) = 1-A318833(n).

Original entry on oeis.org

-1, 0, 0, 2, 0, 7, 0, 6, 6, 13, 0, 13, 0, 19, 22, 10, 0, 19, 0, 23, 32, 31, 0, -3, 20, 37, 24, 33, 0, 21, 0, 6, 52, 49, 58, -36, 0, 55, 62, -9, 0, 29, 0, 53, 52, 67, 0, -87, 42, 53, 82, 63, 0, -29, 94, -15, 92, 85, 0, -219, 0, 91, 74, -22, 112, 45, 0, 83, 112, 45, 0, -257, 0, 109, 82, 93, 136, 53, 0, -165, 42, 121
Offset: 1

Views

Author

Antti Karttunen, Jan 05 2021

Keywords

Crossrefs

Cf. also A340140, A340197 for similar definitions.

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(dA023900(n) = factorback(apply(p -> 1-p, factor(n)[, 1]));
    A318833(n) = (n+A023900(n));
    v340367 = DirInverseCorrect(vector(up_to, n, 1-A318833(n)));
    A340367(n) = v340367[n];
    
  • PARI
    \\ Or as:
    A340367(n) = if(1==n, -1, sumdiv(n, d, if(dA318833(n/d))*A340367(d), 0)));

Formula

a(1) = -1, for n > 1, a(n) = Sum_{d|n, dA318833(n/d)) * a(d).

A319340 Sum of Euler totient function and its Dirichlet inverse: a(n) = A000010(n) + A023900(n).

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 3, 4, 8, 0, 6, 0, 12, 16, 7, 0, 8, 0, 12, 24, 20, 0, 10, 16, 24, 16, 18, 0, 0, 0, 15, 40, 32, 48, 14, 0, 36, 48, 20, 0, 0, 0, 30, 32, 44, 0, 18, 36, 24, 64, 36, 0, 20, 80, 30, 72, 56, 0, 8, 0, 60, 48, 31, 96, 0, 0, 48, 88, 0, 0, 26, 0, 72, 48, 54, 120, 0, 0, 36, 52, 80, 0, 12, 128, 84, 112, 50, 0, 16
Offset: 1

Views

Author

Antti Karttunen, Sep 17 2018

Keywords

Crossrefs

Programs

Formula

a(n) = A000010(n) + A023900(n).
a(n) = A318833(n) - A051953(n).

A318841 a(n) = n - A173557(n).

Original entry on oeis.org

0, 1, 1, 3, 1, 4, 1, 7, 7, 6, 1, 10, 1, 8, 7, 15, 1, 16, 1, 16, 9, 12, 1, 22, 21, 14, 25, 22, 1, 22, 1, 31, 13, 18, 11, 34, 1, 20, 15, 36, 1, 30, 1, 34, 37, 24, 1, 46, 43, 46, 19, 40, 1, 52, 15, 50, 21, 30, 1, 52, 1, 32, 51, 63, 17, 46, 1, 52, 25, 46, 1, 70, 1, 38, 67, 58, 17, 54, 1, 76, 79, 42, 1, 72, 21, 44, 31, 78, 1, 82, 19, 70, 33, 48
Offset: 1

Views

Author

Antti Karttunen, Sep 16 2018

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := n - Times @@ (FactorInteger[n][[;;, 1]] - 1); a[1] = 0; Array[a, 100] (* Amiram Eldar, Dec 16 2023 *)
  • PARI
    A173557(n) = factorback(apply(p -> p-1, factor(n)[, 1]));
    A318841(n) = (n-A173557(n));

Formula

a(n) = n - A173557(n).
Sum_{k=1..n} a(k) ~ c * n^2 / 2, where c = 1 - A307868 = 0.528319... . - Amiram Eldar, Dec 16 2023

A340140 a(1) = -1, for n > 1, a(n) = Sum_{d|n, dA340197(n/d) * a(d).

Original entry on oeis.org

-1, 0, 0, -2, 0, -7, 0, -6, -6, -13, 0, -13, 0, -19, -22, -22, 0, -19, 0, -23, -32, -31, 0, -81, -20, -37, -24, -33, 0, -21, 0, -78, -52, -49, -58, -183, 0, -55, -62, -147, 0, -29, 0, -53, -52, -67, 0, -321, -42, -53, -82, -63, 0, -223, -94, -213, -92, -85, 0, -591, 0, -91, -74, -278, -112, -45, 0, -83, -112, -45, 0, -733
Offset: 1

Views

Author

Antti Karttunen, Jan 05 2021

Keywords

Comments

This seems to differ from 1-A318833(n) at the points given by A033987.

Crossrefs

Programs

Formula

a(1) = -1, for n > 1, a(n) = Sum_{d|n, dA340197(n/d) * a(d).

A340189 a(n) = n + A340187(n).

Original entry on oeis.org

2, 1, 1, 4, 1, 9, 1, 8, 11, 17, 1, 11, 1, 25, 27, 16, 1, 13, 1, 17, 41, 41, 1, 24, 37, 49, 25, 21, 1, 1, 1, 32, 69, 65, 79, 40, 1, 73, 83, 40, 1, -7, 1, 35, 21, 89, 1, 48, 79, 17, 111, 39, 1, 61, 131, 60, 125, 113, 1, 83, 1, 121, 27, 64, 145, -27, 1, 53, 153, -49, 1, 71, 1, 145, 23, 57, 193, -31, 1, 80, 83, 161, 1, 131
Offset: 1

Views

Author

Antti Karttunen, Dec 31 2020

Keywords

Crossrefs

Programs

  • PARI
    up_to = 65537;
    A063994(n) = { my(f=factor(n)); prod(i=1, #f~, gcd(f[i, 1]-1, n-1)); };
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA063994(n)));
    A340187(n) = v340187[n];
    A340189(n) = (n+A340187(n));

Formula

a(n) = n + A340187(n).
a(n) = A340188(n) + A318828(n).
Showing 1-6 of 6 results.