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.

A342539 a(n) = Sum_{k=1..n} phi(gcd(k, n))^n.

Original entry on oeis.org

1, 2, 10, 19, 1028, 132, 279942, 65798, 10078726, 2097160, 100000000010, 16797702, 106993205379084, 156728328204, 35186519703560, 281479271809036, 295147905179352825872, 203119914385420, 708235345355337676357650, 1152924803145924620, 46005163783270994804748, 20000000000000000000020
Offset: 1

Views

Author

Seiichi Manyama, Mar 15 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSum[n, EulerPhi[n/#] * EulerPhi[#]^n &]; Array[a, 20] (* Amiram Eldar, Mar 15 2021 *)
  • PARI
    a(n) = sum(k=1, n, eulerphi(gcd(k, n))^n);
    
  • PARI
    a(n) = sumdiv(n, d, eulerphi(n/d)*eulerphi(d)^n);

Formula

a(n) = Sum_{d|n} phi(n/d) * phi(d)^n.
If p is prime, a(p) = p-1 + (p-1)^p.
a(n) = Sum_{k=1..n} phi(n/gcd(n,k))^(n-1)*phi(gcd(n,k)). - Richard L. Ollerton, May 09 2021

A342541 a(n) = Sum_{k=1..n} phi(gcd(k, n))^(n/gcd(k, n)).

Original entry on oeis.org

1, 2, 4, 5, 8, 10, 12, 14, 28, 28, 20, 62, 24, 54, 272, 68, 32, 198, 36, 676, 1224, 130, 44, 1348, 4136, 180, 3540, 3426, 56, 12632, 60, 1640, 22520, 304, 129456, 22370, 72, 378, 101808, 270952, 80, 192996, 84, 40630, 1867184, 550, 92, 551528, 1679700, 4198860, 2105408
Offset: 1

Views

Author

Seiichi Manyama, Mar 15 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSum[n, EulerPhi[n/#] * EulerPhi[#]^(n/#) &]; Array[a, 50] (* Amiram Eldar, Mar 15 2021 *)
  • PARI
    a(n) = sum(k=1, n, eulerphi(gcd(k, n))^(n/gcd(k, n)));
    
  • PARI
    a(n) = sumdiv(n, d, eulerphi(n/d)*eulerphi(d)^(n/d));

Formula

a(n) = Sum_{d|n} phi(n/d) * phi(d)^(n/d).
If p is prime, a(p) = 2 *(p-1).

A342544 a(n) = Sum_{k=1..n} phi(gcd(k, n))^(gcd(k, n) - 1).

Original entry on oeis.org

1, 2, 6, 11, 260, 40, 46662, 16398, 1679630, 262408, 10000000010, 4194366, 8916100448268, 13060740684, 4398046511640, 35184372105244, 18446744073709551632, 16926661124436, 39346408075296537575442, 144115188076118572, 3833759992447475215524, 1000000000010000000020
Offset: 1

Views

Author

Seiichi Manyama, Mar 15 2021

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := DivisorSum[n, EulerPhi[n/#] * EulerPhi[#]^(# - 1) &]; Array[a, 20] (* Amiram Eldar, Mar 15 2021 *)
  • PARI
    a(n) = sum(k=1, n, eulerphi(gcd(k, n))^(gcd(k, n)-1));
    
  • PARI
    a(n) = sumdiv(n, d, eulerphi(n/d)*eulerphi(d)^(d-1));

Formula

a(n) = Sum_{d|n} phi(n/d) * phi(d)^(d-1).
If p is prime, a(p) = p-1 + (p-1)^(p-1).
Showing 1-3 of 3 results.