A377707 Numbers k that have a record number of divisors d such that gcd(d, k/d) is a square.

1, 2, 6, 30, 210, 1680, 2310, 18480, 30030, 240240, 480480, 3843840, 4084080, 8168160, 65345280, 77597520, 155195040, 1241560320, 1784742960, 3569485920, 28555887360, 51757545840, 103515091680, 828120733440, 1604483921040, 3208967842080, 25671742736640, 51343485473280

Offset

1,2

Comments

Indices of records in A365171.

The corresponding record values are 1, 2, 4, 8, 16, 24, 32, 48, 64, 96, ... (see the link for more values).

Links

Amiram Eldar, Table of n, a(n) for n = 1..102

Amiram Eldar, Table of n, a(n), A365171(a(n)) for n = 1..102

Mathematica

f[p_, e_] := Floor[(e + 3)/4] + Floor[(e + 4)/4]; 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. A365171.

Subsequence of A025487.

Sequence in context: A375526 A372741 A118747 * A375271 A129779 A068215

Adjacent sequences: A377704 A377705 A377706 * A377708 A377709 A377710

Keyword

nonn

Author

Amiram Eldar, Nov 04 2024

Status

approved