decompwlj 3D

Primes in which parity of digits alternates

A030144 on the OEIS · family primes

Weight–level plate of Primes in which parity of digits alternates
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 viewerA030144 on the OEIS
Terms100,000 (n = 1 … 100,000)
Decomposable (a > 2d)99,990
Level class, k > L27,825 · 27.83 %
Weight class, k ≤ L72,165 · 72.17 %
Ties, k = L1
On the level line L = 16,322
Forced level, l ≤ d²1,136
Range of a(n)2 … 323,496,787
Range of the jump d1 … 111,111,126
Largest weight k, level L323,496,457, 107,830,995

561 different gaps occur, from 1 to 111,111,126; the level share is 27.83 %; 1.1 % of terms are forced level (l <= d^2); 10 terms do not decompose.

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.