A308471 Lowest outliers for A057660.

1, 4, 6, 12, 24, 30, 60, 120, 180, 210, 360, 420, 840, 1260, 2520, 4620, 9240, 13860, 27720, 55440, 60060, 120120, 180180, 360360, 720720, 1441440, 1801800, 2042040, 3063060, 6126120, 12252240, 24504480, 30630600, 36756720, 38798760

Offset

1,2

Comments

A057660(n) is a multiplicative function bounded above by n*(n-1)+1, which is reached whenever n is 1 or prime. These numbers are the n such that the ratio between A057660(n) and the upper bound reaches a record low.

Motivated by Daniel Forgues's conjecture that this sequence consists of 4 and A051451.

A subsequence of A025487.

Links

Charlie Neder, Table of n, a(n) for n = 1..215

Example

A057660(60060)/(60060*60059+1) = 1211716737/3607143541 ~ 0.3359214, and every number less than 60060 has a ratio > 0.34, so 60060 is in this sequence.

Crossrefs

Cf. A057660, A025487, A051451.

Sequence in context: A054167 A303198 A120211 * A357809 A162688 A362883

Adjacent sequences: A308468 A308469 A308470 * A308472 A308473 A308474

Keyword

nonn

Author

Charlie Neder, May 29 2019

Status

approved