Numbers n such that 27*n+1 is prime

Open in the 3-D viewerA224467 on the OEIS
| Terms | 100,000 (n = 1 … 100,000) |
|---|---|
| Decomposable (a > 2d) | 99,998 |
| Level class, k > L | 18,660 · 18.66 % |
| Weight class, k ≤ L | 81,338 · 81.34 % |
| Ties, k = L | 1 |
| On the level line L = 1 | 3 |
| Forced level, l ≤ d² | 8 |
| Range of a(n) | 4 … 1,074,430 |
| Range of the jump d | 2 … 124 |
| Largest weight k, level L | 537,071, 358,062 |
48 different gaps occur, from 2 to 124; the level share is 18.66 %; L = 2 holds 47 % 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.