Numbers k such that 6*k+1, 12*k+1 and 18*k+1 are all primes

Open in the 3-D viewerA046025 on the OEIS
| Terms | 100,000 (n = 1 … 100,000) |
|---|---|
| Decomposable (a > 2d) | 99,996 |
| Level class, k > L | 44,691 · 44.69 % |
| Weight class, k ≤ L | 55,305 · 55.31 % |
| Ties, k = L | 2 |
| On the level line L = 1 | 5,773 |
| Forced level, l ≤ d² | 482 |
| Range of a(n) | 1 … 38,188,796 |
| Range of the jump d | 1 … 4,810 |
| Largest weight k, level L | 38,172,389, 18,541,352 |
1,503 different gaps occur, from 1 to 4,810; the level share is 44.69 %.
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.