A365681 Numbers with a record number of exponentially squarefree divisors.

1, 2, 4, 6, 12, 24, 36, 60, 120, 180, 360, 840, 1260, 2520, 6300, 7560, 12600, 27720, 69300, 83160, 138600, 332640, 360360, 900900, 1081080, 1801800, 4324320, 5405400, 12612600, 17297280, 18378360, 30630600, 73513440, 86486400, 91891800, 214414200, 294053760

Offset

1,2

Comments

Indices of records of A365680.

The corresponding record values are 1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 32, 36, 48, 54, 64, 72, 96, ... (see the link for more values).

Links

Amiram Eldar, Table of n, a(n) for n = 1..255

Amiram Eldar, Table of n, a(n), A365680(a(n)) for n = 1..255

Mathematica

f[p_, e_] := Count[Range[e], _?SquareFreeQ] + 1; d[1] = 1; d[n_] := Times @@ f @@@ FactorInteger[n]; v = Cases[Import["https://oeis.org/A025487/b025487.txt", "Table"], {_, _}][[;; , 2]]; seq = {}; dm = 0; Do[If[(dk = d[v[[k]]]) > dm, dm = dk; AppendTo[seq, v[[k]]]], {k, 1, Length[v]}]; seq

Crossrefs

Cf. A365680.

Subsequence of A025487.

Similar sequences: A306736, A307845, A318278.

Sequence in context: A340637 A362782 A365900 * A333665 A355595 A050293

Adjacent sequences: A365678 A365679 A365680 * A365682 A365683 A365684

Keyword

nonn

Author

Amiram Eldar, Sep 15 2023

Status

approved