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.

A318829 a(n) = A063994(n) / A049559(n) = (1/gcd(n-1, phi(n))) * Product_{primes p dividing n} gcd(p-1, n-1).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2
Offset: 1

Views

Author

Antti Karttunen, Sep 09 2018

Keywords

Comments

Records occur at: 1, 15, 85, 247, 671, 949, 1105, 1387, 2047, 2821, 9471, 11305, 13747, 13981, 29341, 40885, 51319, 63973, ...

Crossrefs

Programs

Formula

a(n) = A063994(n) / A049559(n).
a(n) = A160595(n) / A247074(n).

A318827 a(n) = n - gcd(n - 1, phi(n)).

Original entry on oeis.org

0, 1, 1, 3, 1, 5, 1, 7, 7, 9, 1, 11, 1, 13, 13, 15, 1, 17, 1, 19, 17, 21, 1, 23, 21, 25, 25, 25, 1, 29, 1, 31, 29, 33, 33, 35, 1, 37, 37, 39, 1, 41, 1, 43, 41, 45, 1, 47, 43, 49, 49, 49, 1, 53, 53, 55, 53, 57, 1, 59, 1, 61, 61, 63, 49, 61, 1, 67, 65, 67, 1, 71, 1, 73, 73, 73, 73, 77, 1, 79, 79, 81, 1, 83, 81, 85, 85, 87, 1, 89, 73
Offset: 1

Views

Author

Antti Karttunen, Sep 09 2018

Keywords

Comments

a(n) = n-1 for n in A209211.

Crossrefs

Programs

  • Mathematica
    Array[# - GCD[# - 1, EulerPhi[#]] &, 100] (* Alonso del Arte, Sep 09 2018 *)
  • PARI
    A318827(n) = (n-gcd(eulerphi(n), n-1));

Formula

a(n) = n - A049559(n) = n - gcd(n - 1, phi(n)).
a(n) = A051953(n) + A318830(n).
a(p) = 1 for p prime.

A340188 Sum of A063994 and its Dirichlet inverse, where A063994(x) = Product_{primes p dividing x} gcd(p-1, x-1).

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 8, 0, 0, 0, 12, 16, 1, 0, -4, 0, -2, 24, 20, 0, 1, 16, 24, 0, -4, 0, -28, 0, 1, 40, 32, 48, 5, 0, 36, 48, 1, 0, -48, 0, -8, -16, 44, 0, 1, 36, -32, 64, -10, 0, 8, 80, 5, 72, 56, 0, 24, 0, 60, -32, 1, 96, -88, 0, -14, 88, -116, 0, 0, 0, 72, -48, -16, 120, -108, 0, 1, 4, 80, 0, 48, 128, 84, 112
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];
    A340188(n) = (A063994(n)+A340187(n));

Formula

a(n) = A063994(n) + A340187(n).
a(n) = A340189(n) - A318828(n).

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).

A318840 a(n) = phi(n) - Product_{primes p dividing n} gcd(p-1, n-1).

Original entry on oeis.org

0, 0, 0, 1, 0, 1, 0, 3, 4, 3, 0, 3, 0, 5, 4, 7, 0, 5, 0, 7, 8, 9, 0, 7, 16, 11, 16, 9, 0, 7, 0, 15, 16, 15, 20, 11, 0, 17, 20, 15, 0, 11, 0, 19, 16, 21, 0, 15, 36, 19, 28, 21, 0, 17, 36, 23, 32, 27, 0, 15, 0, 29, 32, 31, 32, 15, 0, 31, 40, 21, 0, 23, 0, 35, 36, 33, 56, 23, 0, 31, 52, 39, 0, 23, 48, 41, 52, 39, 0, 23, 36, 43, 56, 45, 68, 31
Offset: 1

Views

Author

Antti Karttunen, Sep 11 2018

Keywords

Crossrefs

Programs

  • PARI
    A063994(n) = { my(f=factor(n)[,1]); prod(i=1, #f, gcd(f[i]-1, n-1)); };
    A318840(n) = (eulerphi(n) - A063994(n));

Formula

a(n) = A000010(n) - A063994(n).
a(n) = A318828(n) - A051953(n).
Showing 1-5 of 5 results.