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 1-4 of 4 results.

A340143 Möbius transform of A160595, where A160595(x) = phi(x)/gcd(phi(x), x-1).

Original entry on oeis.org

1, 0, 0, 1, 0, 1, 0, 2, 2, 3, 0, 1, 0, 5, 3, 4, 0, 2, 0, 3, 2, 9, 0, 2, 4, 11, 6, -3, 0, 0, 0, 8, 4, 15, 11, 4, 0, 17, 11, 6, 0, 3, 0, 9, 0, 21, 0, 4, 6, 12, 15, -5, 0, 6, 19, 18, 8, 27, 0, 3, 0, 29, 13, 16, 2, -11, 0, 15, 10, -12, 0, 8, 0, 35, 12, -7, 14, 0, 0, 12, 18, 39, 0, 13, 15, 41, 27, 18, 0, 12, 3, 21, 14, 45, 35
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2020

Keywords

Crossrefs

Cf. also A340141, A340142.

Programs

  • Mathematica
    Table[DivisorSum[n, MoebiusMu[n/#1]*#2/GCD[#2, #3] & @@ {#, EulerPhi[#], # - 1} &], {n, 95}] (* Michael De Vlieger, Dec 29 2020 *)
  • PARI
    A160595(n) = { my(x=eulerphi(n)); x/gcd(x,n-1); };
    A340143(n) = sumdiv(n,d,moebius(n/d)*A160595(d));

Formula

a(n) = Sum_{d|n} A008683(n/d) * A160595(d).

A340141 Numerators of the sequence whose Dirichlet convolution with itself yields sequence A160595(x) = phi(x)/gcd(phi(x), x-1).

Original entry on oeis.org

1, 1, 1, 7, 1, 3, 1, 25, 11, 7, 1, 19, 1, 11, 7, 363, 1, 31, 1, 43, 5, 19, 1, 63, 19, 23, 61, 3, 1, 15, 1, 1335, 9, 31, 23, 189, 1, 35, 23, 139, 1, 29, 1, 115, 23, 43, 1, 867, 27, 127, 31, 11, 1, 163, 39, 279, 17, 55, 1, 73, 1, 59, 123, 9923, 5, -15, 1, 187, 21, -9, 1, 615, 1, 71, 127, 19, 29, 47, 1, 1875, 1363, 79, 1, 203, 31
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2020

Keywords

Crossrefs

Cf. A046644 (denominators).
Cf. A160595.
Cf. also A340142, A340143.

Programs

  • PARI
    up_to = 65537;
    A160595(n) = { my(x=eulerphi(n)); x/gcd(x,n-1); };
    DirSqrt(v) = {my(n=#v, u=vector(n)); u[1]=1; for(n=2, n, u[n]=(v[n]/v[1] - sumdiv(n, d, if(d>1&&dA160595(n)));
    A340141(n) = numerator(v340141rat[n]);

A340145 Dirichlet inverse of A247074(x) = phi(x)/(Product_{primes p dividing x} gcd(p-1, x-1)).

Original entry on oeis.org

1, -1, -1, -1, -1, 0, -1, -1, -2, -2, -1, 1, -1, -4, 0, -1, -1, 1, -1, 1, -1, -8, -1, 2, -4, -10, -4, 9, -1, 2, -1, -1, -3, -14, -4, 3, -1, -16, -4, 4, -1, 4, -1, 1, 4, -20, -1, 3, -6, -5, -6, 17, -1, 4, -8, -10, -7, -26, -1, 6, -1, -28, 0, -1, -1, 24, -1, 1, -9, 18, -1, 4, -1, -34, 1, 25, -13, 10, -1, 7, -8, -38, -1
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2020

Keywords

Crossrefs

Cf. A247074.
Cf. also A340142, A340144, A340146.

Programs

  • PARI
    up_to = 65537;
    A247074(n) = { my(f=factor(n)); eulerphi(f)/prod(i=1, #f~, gcd(f[i, 1]-1, n-1)); }; \\ From A247074
    DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA247074(n)));
    A340145(n) = v340145[n];

A340187 Dirichlet inverse of A063994(x) = Product_{primes p dividing x} gcd(p-1, x-1).

Original entry on oeis.org

1, -1, -2, 0, -4, 3, -6, 0, 2, 7, -10, -1, -12, 11, 12, 0, -16, -5, -18, -3, 20, 19, -22, 0, 12, 23, -2, -7, -28, -29, -30, 0, 36, 31, 44, 4, -36, 35, 44, 0, -40, -49, -42, -9, -24, 43, -46, 0, 30, -33, 60, -13, -52, 7, 76, 4, 68, 55, -58, 23, -60, 59, -36, 0, 80, -93, -66, -15, 84, -119, -70, -1, -72, 71, -52, -19
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];
Showing 1-4 of 4 results.