Block #2,931,698

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.

1.555 × 10⁹⁹(100-digit number)

15551398943969841332…40933045369765887999

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

1.555 × 10⁹⁹(100-digit number)

15551398943969841332…40933045369765887999

Verify on FactorDB ↗Wolfram Alpha ↗

origin + 1

1.555 × 10⁹⁹(100-digit number)

15551398943969841332…40933045369765888001

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

3.110 × 10⁹⁹(100-digit number)

31102797887939682664…81866090739531775999

Verify on FactorDB ↗Wolfram Alpha ↗

2^1 × origin + 1

3.110 × 10⁹⁹(100-digit number)

31102797887939682664…81866090739531776001

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

6.220 × 10⁹⁹(100-digit number)

62205595775879365329…63732181479063551999

Verify on FactorDB ↗Wolfram Alpha ↗

2^2 × origin + 1

6.220 × 10⁹⁹(100-digit number)

62205595775879365329…63732181479063552001

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

1.244 × 10¹⁰⁰(101-digit number)

12441119155175873065…27464362958127103999

Verify on FactorDB ↗Wolfram Alpha ↗

2^3 × origin + 1

1.244 × 10¹⁰⁰(101-digit number)

12441119155175873065…27464362958127104001

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

2.488 × 10¹⁰⁰(101-digit number)

24882238310351746131…54928725916254207999

Verify on FactorDB ↗Wolfram Alpha ↗

2^4 × origin + 1

2.488 × 10¹⁰⁰(101-digit number)

24882238310351746131…54928725916254208001

Verify on FactorDB ↗Wolfram Alpha ↗

Difference: 2^4 × origin + 1 − 2^4 × origin − 1 = 2 (twin primes ✓)

Level 5 — Twin Prime Pair (2^5 × origin ± 1)

2^5 × origin − 1

4.976 × 10¹⁰⁰(101-digit number)

49764476620703492263…09857451832508415999

Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 11 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

RareChain length 11

Approximately 1 in 1,000 blocks. Noteworthy discoveries.

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

Block #2,931,698

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