Block #324,905

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 12/22/2013, 4:08:00 PM · Difficulty 10.2060 · 6,470,846 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
958979a6ed2fc73f70c6e62d9c8382eca2972c40deea771d6c74c7c8713be328

Height

#324,905

Difficulty

10.206014

Transactions

31

Size

12.11 KB

Version

2

Bits

0a34bd5b

Nonce

155,610

Timestamp

12/22/2013, 4:08:00 PM

Confirmations

6,470,846

Merkle Root

b934766f236ee4d25a9ac83f3a2c1adf9375f186be69e7bf4878a204adaed2ee
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.

4.724 × 10⁹⁸(99-digit number)
47248429144309967717…35023600003443624481
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
4.724 × 10⁹⁸(99-digit number)
47248429144309967717…35023600003443624481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
9.449 × 10⁹⁸(99-digit number)
94496858288619935434…70047200006887248961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
1.889 × 10⁹⁹(100-digit number)
18899371657723987086…40094400013774497921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
3.779 × 10⁹⁹(100-digit number)
37798743315447974173…80188800027548995841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
7.559 × 10⁹⁹(100-digit number)
75597486630895948347…60377600055097991681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
1.511 × 10¹⁰⁰(101-digit number)
15119497326179189669…20755200110195983361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
3.023 × 10¹⁰⁰(101-digit number)
30238994652358379339…41510400220391966721
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
6.047 × 10¹⁰⁰(101-digit number)
60477989304716758678…83020800440783933441
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.209 × 10¹⁰¹(102-digit number)
12095597860943351735…66041600881567866881
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
2.419 × 10¹⁰¹(102-digit number)
24191195721886703471…32083201763135733761
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:57,610,087 XPM·at block #6,795,750 · updates every 60s
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