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.

A362184 Record values in A362183.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 16, 17, 21, 23, 25, 26, 27, 31, 33, 34, 37, 38, 45, 49, 54, 59, 62, 64, 71, 80, 81, 84, 92, 99, 106, 122, 137, 145, 147, 167, 174, 180, 183, 203, 211, 231, 232, 251, 253, 283, 289, 306, 318, 342, 362, 378, 410, 412, 453
Offset: 1

Views

Author

Amiram Eldar, Apr 10 2023

Keywords

Crossrefs

The unitary version of A101373.
Similar sequences: A131934, A361971.

Programs

  • Mathematica
    ucototient[n_] := n - Times @@ (Power @@@ FactorInteger[n] - 1); ucototient[1] = 0; With[{max = 300}, solnum = Table[0, {n, 1, max}]; Do[If[(i = ucototient[k]) <= max, solnum[[i]]++], {k, 2, max^2}]; s = {1}; solmax=1; Do[sol = solnum[[k]]; If[sol > solmax, solmax = sol; AppendTo[s, sol]], {k, 2, max}]; s]

Formula

a(n) = A362181(A362183(n)).

A362181 Number of numbers k such that A323410(k) = n.

Original entry on oeis.org

0, 0, 1, 0, 2, 1, 2, 1, 3, 1, 3, 2, 3, 3, 2, 2, 3, 3, 4, 3, 3, 3, 3, 3, 4, 4, 3, 3, 4, 5, 4, 5, 4, 5, 3, 4, 4, 5, 3, 5, 3, 5, 5, 5, 4, 6, 4, 6, 4, 6, 2, 7, 4, 6, 4, 6, 3, 7, 3, 5, 4, 6, 3, 8, 2, 6, 6, 7, 4, 8, 4, 6, 6, 7, 3, 9, 4, 7, 4, 5, 5, 9, 6, 9, 4, 7, 3
Offset: 2

Views

Author

Amiram Eldar, Apr 10 2023

Keywords

Comments

The offset is 2 since A323410(p) = 1 for all prime powers p (A246655).
a(0) = 1, since there is only one solution, x = 1, to A323410(x) = 0.

Crossrefs

Row lengths of A362180.
The unitary version of A063740.
Cf. A246655, A323410, A362182 (positions of 0's), A362183 (indices of records), A362184, A362185 (positions of 1's), A362186.
Similar sequences: A014197, A361967.

Programs

  • Mathematica
    ucototient[n_] := n - Times @@ (Power @@@ FactorInteger[n] - 1); ucototient[1] = 0; With[{max = 100}, ucot = Table[ucototient[n], {n, 1, max^2}]; Table[Length[Position[ucot, n]], {n, 2, max}] // Flatten]

Formula

a(A362182(n)) = 0.
a(A362185(n)) = 1.
a(A362186(n)) = n.

A362487 Infinitary highly totient numbers: numbers k that have more solutions x to the equation iphi(x) = k than any smaller k, where iphi is the infinitary totient function A091732.

Original entry on oeis.org

1, 6, 12, 24, 48, 96, 144, 240, 288, 480, 576, 720, 1152, 1440, 2880, 4320, 5760, 8640, 11520, 17280, 34560, 51840, 69120, 103680, 120960, 172800, 207360, 241920, 345600, 362880, 414720, 483840, 725760, 967680, 1209600, 1451520, 1935360, 2419200, 2903040, 3628800
Offset: 1

Views

Author

Amiram Eldar, Apr 22 2023

Keywords

Comments

Indices of records of A362485.
The corresponding numbers of solutions are 2, 4, 6, 10, 14, 18, 22, ... (A362488).

Crossrefs

Programs

  • Mathematica
    solnum[n_] := Length[invIPhi[n]]; seq[kmax_] := Module[{s = {}, solmax=0}, Do[sol = solnum[k]; If[sol > solmax, solmax = sol; AppendTo[s, k]], {k, 1, kmax}]; s]; seq[10^4] (* using the function invIPhi from A362484 *)
Showing 1-3 of 3 results.