Block #337,493

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 12/31/2013, 5:31:38 PM · Difficulty 10.1353 · 6,469,379 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
8181a9a952cbffa89a359a0e244edecf708c246b8a1163d95b51cb27a1ca0cd0

Height

#337,493

Difficulty

10.135260

Transactions

17

Size

4.45 KB

Version

2

Bits

0a22a066

Nonce

539,408

Timestamp

12/31/2013, 5:31:38 PM

Confirmations

6,469,379

Merkle Root

4e4459f1ae536a35158c0d4b4af082fa45e7a522f406e670fa9e7a61ce1a3eed
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.

5.767 × 10⁹³(94-digit number)
57674457645937182115…40952863287429910241
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
5.767 × 10⁹³(94-digit number)
57674457645937182115…40952863287429910241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.153 × 10⁹⁴(95-digit number)
11534891529187436423…81905726574859820481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
2.306 × 10⁹⁴(95-digit number)
23069783058374872846…63811453149719640961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
4.613 × 10⁹⁴(95-digit number)
46139566116749745692…27622906299439281921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
9.227 × 10⁹⁴(95-digit number)
92279132233499491384…55245812598878563841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
1.845 × 10⁹⁵(96-digit number)
18455826446699898276…10491625197757127681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
3.691 × 10⁹⁵(96-digit number)
36911652893399796553…20983250395514255361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
7.382 × 10⁹⁵(96-digit number)
73823305786799593107…41966500791028510721
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.476 × 10⁹⁶(97-digit number)
14764661157359918621…83933001582057021441
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
2.952 × 10⁹⁶(97-digit number)
29529322314719837243…67866003164114042881
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:57,699,083 XPM·at block #6,806,871 · updates every 60s
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