Stern Prime Checker

p ≠ q + 2ab?

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About Stern Prime Checker

A Stern prime checker testing if a prime p cannot be written as q + 2ab where q is a smaller prime and a,b ≥ 1. Known Stern primes: 2,3,17,137,227,977,1187,1493... Only finitely many are conjectured to exist. Client-side.

Stern Prime Checker Features

  • Stern test
  • Decomposition check
  • Prime list
  • Known Stern primes
  • Statistics
Stern primes: prime p where p≠q+2ab for any smaller prime q and a,b≥1. Known: 2,3,17,137,227,977,1187,1493... Conjectured finite — possibly only finitely many exist. Related to the Goldbach conjecture and additive number theory.

How to Use

Enter a prime:

  • Test: Is it a Stern prime?
  • Decompositions: Show q+2ab forms
  • Known list: All known Sterns

Rarity

As primes grow, they become easier to decompose as q+2ab. Most large primes have MANY such representations. Stern primes resist ALL of them — an increasingly rare property. The conjecture says this becomes impossible beyond some bound.

Connections

Related to Goldbach: if every even number ≥4 is a sum of two primes, then for p=q+2ab, we need q prime and 2ab even. Stern primes are the 'hardest' primes for this kind of additive decomposition.

Step-by-Step Instructions

  1. 1Enter prime.
  2. 2Check all q+2ab.
  3. 3Determine Stern.
  4. 4View known list.
  5. 5See statistics.

Stern Prime Checker — Frequently Asked Questions

How many Stern primes are there?+

Only 8 are known: 2, 3, 17, 137, 227, 977, 1187, 1493. It's conjectured that these are ALL of them — that no more Stern primes exist. Verified up to very large bounds.

What does the decomposition test check?+

For prime p, we check ALL smaller primes q and ALL a,b≥1 with q+2ab=p. If even ONE such decomposition exists, p is NOT Stern. Only if NO decomposition works is p Stern. For large p, there are exponentially many decompositions to try.

Why is finiteness conjectured?+

Heuristically: as p grows, the number of ways to write p=q+2ab grows rapidly (roughly like p·log(p)). The 'probability' that all decompositions fail decreases super-exponentially. So beyond some point, no prime can be Stern.

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