decompwlj 3D

Primes of the form x^2 + 1320*y^2

A139666 on the OEIS · family quadratic form

Weight–level plate of Primes of the form x^2 + 1320*y^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 viewerA139666 on the OEIS
Terms100,000 (n = 1 … 100,000)
Decomposable (a > 2d)100,000
Level class, k > L58,591 · 58.59 %
Weight class, k ≤ L41,409 · 41.41 %
Ties, k = L68
On the level line L = 122,941
Forced level, l ≤ d²823
Range of a(n)1,321 … 53,814,841
Range of the jump d48 … 6,000
Largest weight k, level L53,810,857, 1,082,497

114 different gaps occur, from 48 to 6,000; the level share is 58.59 %; L = 1 holds 39 % 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.