decompwlj 3D

Numbers that are divisible by exactly three different primes

A033992 on the OEIS · family multiplicative · also known as Exactly three distinct prime factors

Weight–level plate of Numbers that are divisible by exactly three different primes
Click the plate to explore it in 3-D. Weight k across, level L up, both on log scales: blue in the weight class (k ≤ L), orange in the level class (k > L). The dashed diagonal is k = L.
Open in the 3-D viewerA033992 on the OEIS
Terms100,000 (n = 1 … 100,000)
Decomposable (a > 2d)100,000
Level class, k > L13,550 · 13.55 %
Weight class, k ≤ L86,450 · 86.45 %
Ties, k = L40
On the level line L = 18,117
Forced level, l ≤ d²5
Range of a(n)30 … 258,764
Range of the jump d1 … 24
Largest weight k, level L258,707, 129,377

Exactly three distinct prime factors, any exponents. The level share is 13.55 %; L = 1 holds 60 % of the level class.

The decomposition

Every term of a strictly increasing sequence is written a(n) = k(n)·L(n) + d(n): the jump d = a(n+1) − a(n), the weight k the least divisor of a − d greater than d, the level L = (a − d)/k. A term decomposes when a > 2d; it is in the level class when k > L and in the weight class when k ≤ L. See decompwlj.com and arXiv:0711.0865, or how it works, with worked examples and a live one.