decompwlj 3D

Ternary sieve: delete every 3rd number, then every 9th, 27th, etc

A007951 on the OEIS · family sieve

Weight–level plate of Ternary sieve: delete every 3rd number, then every 9th, 27th, etc
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 viewerA007951 on the OEIS
Terms100,000 (n = 1 … 100,000)
Decomposable (a > 2d)99,998
Level class, k > L3,513 · 3.51 %
Weight class, k ≤ L96,485 · 96.49 %
Ties, k = L13
On the level line L = 12,178
Forced level, l ≤ d²2
Range of a(n)1 … 178,522
Range of the jump d1 … 8
Largest weight k, level L178,397, 89,259

8 different gaps occur, from 1 to 8; the level share is 3.51 %; L = 1 holds 62 % 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.