A348414 Numbers with record values of the denominator of the harmonic mean of their divisors.

1, 2, 4, 8, 16, 36, 64, 100, 128, 144, 256, 324, 400, 512, 576, 900, 1296, 1600, 1936, 2304, 3600, 5184, 6400, 8100, 9216, 10404, 11664, 14400, 17424, 20736, 22500, 30276, 32400, 41616, 46656, 57600, 76176, 90000, 108900, 129600, 166464, 202500, 230400, 260100

Offset

1,2

Comments

The corresponding record values are 1, 3, 7, 15, 31, 91, 127, 217, 255, 403, ... (see the link for more values).

Links

Amiram Eldar, Table of n, a(n) for n = 1..200

Amiram Eldar, Table of n, a(n), A099378(a(n)) for n = 1..200

Example

The first 4 terms of A099378 are 1, 3, 2 and 7. The record values, 1, 3 and 7, occur at 1, 2 and 4, the first 3 terms of this sequence.

Mathematica

d[n_] := Denominator[DivisorSigma[0, n]/DivisorSigma[-1, n]]; dm = 0; s = {}; Do[dn = d[n]; If[dn > dm, dm = dn; AppendTo[s, n]], {n, 1, 10^6}]; s

Crossrefs

Cf. A099377, A099378.

Sequence in context: A085294 A195327 A266544 * A333051 A034340 A034341

Adjacent sequences: A348411 A348412 A348413 * A348415 A348416 A348417

Keyword

nonn

Author

Amiram Eldar, Oct 17 2021

Status

approved