decompwlj 3D

Semiprimes p*q for which p <= q < p^2

A251728 on the OEIS · family multiplicative

Weight–level plate of Semiprimes p*q for which p <= q < p^2
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 viewerA251728 on the OEIS
Terms100,000 (n = 1 … 100,000)
Decomposable (a > 2d)99,997
Level class, k > L26,437 · 26.44 %
Weight class, k ≤ L73,560 · 73.56 %
Ties, k = L11
On the level line L = 17,944
Forced level, l ≤ d²24
Range of a(n)4 … 2,063,927
Range of the jump d2 … 184
Largest weight k, level L2,063,807, 687,769

86 different gaps occur, from 2 to 184; the level share is 26.44 %; L = 1 holds 30 % 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.