Block #319,914

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 12/19/2013, 8:00:28 AM · Difficulty 10.1752 · 6,520,136 confirmations

2CC
Cunningham Chain of the Second Kind

A sequence where each prime is double the previous prime minus one.

Block Header
Block Hash
401bf63d08e75951c4745e5cd36fa7143084f3f6d42b04f51e75d95a2d1e3ad9

Height

#319,914

Difficulty

10.175214

Transactions

19

Size

6.25 KB

Version

2

Bits

0a2cdad5

Nonce

7,120

Timestamp

12/19/2013, 8:00:28 AM

Confirmations

6,520,136

Merkle Root

ffe405cc5b71deb9b2535a70ddc8fee87ab465ab0f4c352899e067c958108733
Prime Chain Origin

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.

1.366 × 10⁹⁷(98-digit number)
13669983484128597238…88337001092979456001
Discovered Prime Numbers
p_k = 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.

1
origin + 1
1.366 × 10⁹⁷(98-digit number)
13669983484128597238…88337001092979456001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
2.733 × 10⁹⁷(98-digit number)
27339966968257194477…76674002185958912001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
5.467 × 10⁹⁷(98-digit number)
54679933936514388954…53348004371917824001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.093 × 10⁹⁸(99-digit number)
10935986787302877790…06696008743835648001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
2.187 × 10⁹⁸(99-digit number)
21871973574605755581…13392017487671296001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
4.374 × 10⁹⁸(99-digit number)
43743947149211511163…26784034975342592001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
8.748 × 10⁹⁸(99-digit number)
87487894298423022327…53568069950685184001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.749 × 10⁹⁹(100-digit number)
17497578859684604465…07136139901370368001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
3.499 × 10⁹⁹(100-digit number)
34995157719369208931…14272279802740736001
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
6.999 × 10⁹⁹(100-digit number)
69990315438738417862…28544559605481472001
Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 10 consecutive prime numbers forming a Cunningham Chain of the Second Kind. 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
UncommonChain length 10

Roughly 1 in 100 blocks. Solid but expected in a healthy network.

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 2CC formula:

2CC: p₁ (first prime), p₂ = 2p₁ − 1, p₃ = 2p₂ − 1, …
Circulating Supply:57,964,708 XPM·at block #6,840,049 · updates every 60s
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