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

Author

Charlie Neder, May 29 2019

Keywords

• nonn

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.

Examples

			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.
		

Links

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

Crossrefs

Cf. A057660, A025487, A051451.