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.

A331177 Number of values of k, 1 <= k <= n, with A319677(k) = A319677(n), where A319677(n) = n/gcd(n, uphi(n)), and uphi is unitary totient function (A047994).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 3, 3, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 3, 1, 2, 3, 1, 1, 4, 1, 1, 1, 2, 1, 2, 1, 2, 1, 4, 1, 2, 3, 2, 3, 2, 1, 4, 1, 2, 1, 1, 1, 2, 1, 3, 1, 2, 1, 3, 1, 2, 3, 1, 1, 5, 1, 3, 1, 2, 1, 5, 1, 2, 1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 1, 2, 1, 4, 1, 2, 1, 1, 3
Offset: 1

Views

Author

Antti Karttunen, Jan 11 2020

Keywords

Comments

Ordinal transform of A319677.

Crossrefs

Cf. also A330739, A331175.

Programs

  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A047994(n) = { my(f=factor(n)); prod(i=1, #f~, (f[i, 1]^f[i, 2])-1); };
    A319677(n) = n/gcd(n, A047994(n));
    v331177 = ordinal_transform(vector(up_to, n, A319677(n)));
    A331177(n) = v331177[n];

A330746 Number of values of k, 1 <= k <= n, with A017666(k) = A017666(n), where A017666(n) = n/gcd(n, sigma(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 3, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 4, 1, 1, 3, 2, 1, 1, 1, 2, 1, 2, 1, 3, 1, 4, 1, 2, 1, 1, 1, 1, 3, 1, 1, 2, 1, 4, 1, 2, 1, 5, 1, 2, 1, 1, 1, 5, 1, 1, 3, 2, 1, 1, 1, 2, 1, 3, 1, 3, 1, 1, 1, 2, 1, 3, 1, 2, 3, 1, 1, 6, 4, 4, 1, 2, 4, 2, 1, 1, 1, 1, 1, 4, 1, 1, 3
Offset: 1

Views

Author

Antti Karttunen, Jan 11 2020

Keywords

Comments

Ordinal transform of A017666.

Crossrefs

A left inverse of following sequences: A007691, A159907, A245775.
Cf. also A331175.

Programs

  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A017666(n) = (n/gcd(n, sigma(n)));
    v330746 = ordinal_transform(vector(up_to, n, A017666(n)));
    A330746(n) = v330746[n];

Formula

For all n >= 1, a(A014567(n)) = 1.
For all n >= 1, a(A007691(n)) = a(A159907(n)) = a(A245775(n)) = n.

A331178 Number of values of k, 1 <= k <= n, with A023900(k) = A023900(n), where A023900 is Dirichlet inverse of Euler totient function phi.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 2, 1, 1, 1, 4, 1, 3, 1, 2, 1, 1, 1, 4, 2, 2, 3, 2, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 2, 3, 1, 2, 1, 2, 2, 1, 1, 6, 2, 4, 1, 3, 1, 7, 1, 3, 1, 1, 1, 2, 1, 1, 4, 6, 1, 1, 1, 2, 1, 1, 1, 8, 1, 2, 3, 2, 1, 2, 1, 5, 4, 2, 1, 3, 1, 1, 1, 3, 1, 3, 1, 2, 2, 1, 2, 9, 1, 4, 2, 6, 1, 1, 1, 5, 1
Offset: 1

Views

Author

Antti Karttunen, Jan 11 2020

Keywords

Comments

Ordinal transform of A023900.

Crossrefs

Programs

  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A023900(n) = factorback(apply(p -> 1-p, factor(n)[, 1]));
    v331178 = ordinal_transform(vector(up_to, n, A023900(n)));
    A331178(n) = v331178[n];

A331182 Number of values of k, 1 <= k <= n, with A083254(k) = A083254(n), where A083254(n) = 2*phi(n) - n.

Original entry on oeis.org

1, 1, 2, 2, 1, 1, 1, 3, 2, 2, 1, 1, 1, 3, 3, 4, 1, 1, 1, 2, 3, 4, 1, 1, 2, 5, 2, 3, 1, 1, 1, 5, 1, 6, 1, 1, 1, 7, 3, 2, 1, 1, 1, 4, 4, 8, 1, 1, 2, 1, 2, 5, 1, 2, 1, 3, 3, 9, 1, 1, 1, 10, 4, 6, 1, 1, 1, 6, 1, 1, 1, 1, 1, 11, 2, 7, 1, 1, 1, 2, 2, 12, 1, 1, 2, 13, 2, 4, 1, 1, 1, 8, 3, 14, 1, 1, 1, 2, 2, 1, 1, 1, 1, 5, 1
Offset: 1

Views

Author

Antti Karttunen, Jan 11 2020

Keywords

Comments

Ordinal transform of A083254.

Crossrefs

Programs

  • Mathematica
    Module[{b}, b[_] = 0;
    a[n_] := With[{t = 2 EulerPhi[n] - n}, b[t] = b[t] + 1]];
    Array[a, 105] (* Jean-François Alcover, Jan 12 2022 *)
  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A083254(n) = (2*eulerphi(n)-n);
    v331182 = ordinal_transform(vector(up_to,n,A083254(n)));
    A331182(n) = v331182[n];

A331179 Number of values of k, 1 <= k <= n, with A173557(k) = A173557(n), where A173557(n) = Product_{p-1 | p is prime and divisor of n}.

Original entry on oeis.org

1, 2, 1, 3, 1, 2, 1, 4, 3, 2, 1, 4, 1, 2, 1, 5, 1, 5, 1, 3, 2, 2, 1, 6, 4, 3, 7, 3, 1, 2, 1, 6, 1, 2, 1, 8, 1, 2, 2, 5, 1, 4, 1, 3, 3, 2, 1, 9, 4, 6, 1, 5, 1, 10, 2, 5, 2, 2, 1, 4, 1, 2, 6, 7, 1, 2, 1, 3, 1, 3, 1, 11, 1, 3, 5, 3, 2, 4, 1, 7, 12, 3, 1, 7, 1, 2, 1, 4, 1, 6, 2, 3, 3, 2, 3, 13, 1, 6, 3, 8, 1, 2, 1, 8, 2
Offset: 1

Views

Author

Antti Karttunen, Jan 11 2020

Keywords

Comments

Ordinal transform of A173557.

Crossrefs

Cf. A173557.
Cf. also A081373, A331175, A331178.

Programs

  • Mathematica
    A173557[n_] := If[n == 1, 1, Times @@ (FactorInteger[n][[All, 1]] - 1)];
    Module[{b}, b[_] = 0;
    a[n_] := With[{t = A173557[n]}, b[t] = b[t] + 1]];
    Array[a, 105] (* Jean-François Alcover, Jan 12 2022 *)
  • PARI
    up_to = 65537;
    ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om,invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om,invec[i],(1+pt))); outvec; };
    A173557(n) = factorback(apply(p -> p-1, factor(n)[, 1]));
    v331179 = ordinal_transform(vector(up_to, n, A173557(n)));
    A331179(n) = v331179[n];
Showing 1-5 of 5 results.