decompwlj 3D

Primes p such that 10*p + 9 is also prime

A023240 on the OEIS · family primes

Weight–level plate of Primes p such that 10*p + 9 is also 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 viewerA023240 on the OEIS
Terms100,000 (n = 1 … 100,000)
Decomposable (a > 2d)99,997
Level class, k > L35,080 · 35.08 %
Weight class, k ≤ L64,917 · 64.92 %
Ties, k = L10
On the level line L = 18,289
Forced level, l ≤ d²51
Range of a(n)2 … 7,066,249
Range of the jump d2 … 1,022
Largest weight k, level L7,065,389, 2,353,595

292 different gaps occur, from 2 to 1,022; the level share is 35.08 %.

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.