Why can a prime-gap trajectory converge to a future value before that value appears as a prime?
问题内容
I am studying a deterministic construction based on the consecutive gaps between primes.
The phenomenon I am interested in is NOT that arithmetic on primes sometimes produces another prime. The interesting point is that the same future value can be generated by different rows of a cumulative prime-gap construction before that value itself appears in the prime sequence.
Let $p_n$ be the $n$-th prime, and let
$$ g_n=p_n-p_{n-1}. $$
Define the cumulative gap sum
$$ S_n=\sum_{i=2}^{n} g_i=p_n-2, $$
and then define
$$ V_n=S_n+g_n=p_n+2g_n-2. $$
A convergence occurs when two different rows produce the same value $V$.
For example, consider $V=103$. The relevant prime-gap sequence is
$$ 89\xrightarrow{8}97\xrightarrow{4}101\xrightarrow{2}103. $$
The corresponding rows give
$$ 95+8=103 $$
and
$$ 99+4=103. $$
The important chronological point is that the second occurrence of $V=103$ happens when the current prime is $97$.
At that moment, $103$ has not yet appeared in the prime sequence. Nevertheless, the construction has already determined the future value $V=103$. The actual sequence then continues
$$ 97\rightarrow101\rightarrow103. $$
So the value $103$ is determined before the prime $103$ itself appears.
The same construction can also announce a composite value. For example,
$$ 395+8=403, \qquad 399+4=403, $$
while
$$ 403=13\cdot31. $$
Thus the phenomenon is not simply that an arithmetic operation happens to produce a prime. The construction can determine a future integer $V$ before $V$ appears in the prime sequence, whether $V$ eventually turns out to be prime or composite.
There is also a simple algebraic relation behind consecutive convergences. If
$$ V_n=V_{n+1}, $$
then
$$ p_n+2g_n-2=p_{n+1}+2g_{n+1}-2. $$
Since $p_{n+1}=p_n+g_{n+1}$, this gives
$$ g_n=2g_{n+1}. $$
This explains the halving structure $8,4,2$ in the $103$ example.
My question is:
Is there a known number-theoretic interpretation or theorem describing this phenomenon?
In particular, when the same value $V$ is produced on consecutive rows, is there a known result explaining why the corresponding prime gaps must form a halving chain such as
$$ 8,4,2, $$
$$ 16,8,4,2, $$
or
$$ 32,16,8,4,2? $$
More specifically, what mathematical structure determines the fact that the repeated value $V$ is already fixed before the prime $V$ itself appears?
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