decompwlj 3D

Numbers n such that 10n^2 - 1 is prime

A143829 on the OEIS · family prime values

Weight–level plate of Numbers n such that 10n^2 - 1 is prime
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 viewerA143829 on the OEIS
Terms100,000 (n = 1 … 100,000)
Decomposable (a > 2d)99,997
Level class, k > L18,780 · 18.78 %
Weight class, k ≤ L81,217 · 81.22 %
Ties, k = L1
On the level line L = 13
Forced level, l ≤ d²16
Range of a(n)3 … 1,724,391
Range of the jump d3 … 189
Largest weight k, level L574,727, 430,917

54 different gaps occur, from 3 to 189; the level share is 18.78 %; L = 3 holds 44 % 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.