Block #204,158

This is the prime chain origin stored in the block header. It is a composite number (not prime itself) — it equals the first prime in the chain multiplied by a primorial. The origin anchors the entire chain to this specific block.

1.209 × 10⁹⁶(97-digit number)

12099086108650778121…62030686489090029279

Discovered Prime Numbers

Lower: 2^k × origin − 1 | Upper: 2^k × origin + 1

These are the actual prime numbers discovered by this block, computed using the verified Primecoin formula. Each number has been independently confirmed to pass the Fermat primality test. Use the FactorDB links to verify any number independently.

Level 0 — Twin Prime Pair (origin ± 1)

origin − 1

1.209 × 10⁹⁶(97-digit number)

12099086108650778121…62030686489090029279

Verify on FactorDB ↗Wolfram Alpha ↗

origin + 1

1.209 × 10⁹⁶(97-digit number)

12099086108650778121…62030686489090029281

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: origin + 1 − origin − 1 = 2 (twin primes ✓)

Level 1 — Twin Prime Pair (2^1 × origin ± 1)

2^1 × origin − 1

2.419 × 10⁹⁶(97-digit number)

24198172217301556243…24061372978180058559

Verify on FactorDB ↗Wolfram Alpha ↗

2^1 × origin + 1

2.419 × 10⁹⁶(97-digit number)

24198172217301556243…24061372978180058561

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^1 × origin + 1 − 2^1 × origin − 1 = 2 (twin primes ✓)

Level 2 — Twin Prime Pair (2^2 × origin ± 1)

2^2 × origin − 1

4.839 × 10⁹⁶(97-digit number)

48396344434603112487…48122745956360117119

Verify on FactorDB ↗Wolfram Alpha ↗

2^2 × origin + 1

4.839 × 10⁹⁶(97-digit number)

48396344434603112487…48122745956360117121

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^2 × origin + 1 − 2^2 × origin − 1 = 2 (twin primes ✓)

Level 3 — Twin Prime Pair (2^3 × origin ± 1)

2^3 × origin − 1

9.679 × 10⁹⁶(97-digit number)

96792688869206224974…96245491912720234239

Verify on FactorDB ↗Wolfram Alpha ↗

2^3 × origin + 1

9.679 × 10⁹⁶(97-digit number)

96792688869206224974…96245491912720234241

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^3 × origin + 1 − 2^3 × origin − 1 = 2 (twin primes ✓)

Level 4 — Twin Prime Pair (2^4 × origin ± 1)

2^4 × origin − 1

1.935 × 10⁹⁷(98-digit number)

19358537773841244994…92490983825440468479

Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 9 consecutive prime numbers forming a Bi-Twin Chain. The prime chain origin — the large number shown above — anchors the chain and is divisible by a primorial (the product of small primes), cryptographically tying these prime numbers to this specific block.

★☆☆☆☆

Rarity

CommonChain length 9

Found in most blocks. The baseline for Primecoin's proof-of-work.

How Primecoin's Proof-of-Work Constructs These Primes

Primecoin stores a value called the prime chain origin in each block. The miner found a large integer such that when divided by a primorial (the product of small primes: 2 × 3 × 5 × 7 × …), the result is the first prime in the chain. The origin is deliberately divisible by this primorial — that divisibility is part of the proof.

Prime Chain Origin = First Prime × Primorial (2·3·5·7·11·…)

Source: Primecoin prime.cpp — CheckPrimeProofOfWork()

This is why the origin has many small prime factors — those factors are the primorial divisor. The chain then extends from the first prime using the TWN formula:

TWN: twin pairs (p, p+2) where p = origin/primorial − 1 and p+2 = origin/primorial + 1

Cross-reference on Chainz Explorer