Block #329,276

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 12/25/2013, 8:41:09 PM · Difficulty 10.1717 · 6,481,625 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
43ad999bb9ef790d9c2cb5b97f0f9278e26bf1b3e9bed55a27bdff1181fe2d38

Height

#329,276

Difficulty

10.171658

Transactions

12

Size

2.84 KB

Version

2

Bits

0a2bf1c8

Nonce

516,339

Timestamp

12/25/2013, 8:41:09 PM

Confirmations

6,481,625

Merkle Root

63ea8dfc09ee7f94b6c7f7a32aeeb426dca0de98977fd1c05d9031464a185b5b
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.

6.880 × 10¹⁰¹(102-digit number)
68805755991831132253…86981133572560533941
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
6.880 × 10¹⁰¹(102-digit number)
68805755991831132253…86981133572560533941
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.376 × 10¹⁰²(103-digit number)
13761151198366226450…73962267145121067881
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
2.752 × 10¹⁰²(103-digit number)
27522302396732452901…47924534290242135761
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
5.504 × 10¹⁰²(103-digit number)
55044604793464905802…95849068580484271521
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
1.100 × 10¹⁰³(104-digit number)
11008920958692981160…91698137160968543041
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
2.201 × 10¹⁰³(104-digit number)
22017841917385962321…83396274321937086081
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
4.403 × 10¹⁰³(104-digit number)
44035683834771924642…66792548643874172161
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
8.807 × 10¹⁰³(104-digit number)
88071367669543849284…33585097287748344321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.761 × 10¹⁰⁴(105-digit number)
17614273533908769856…67170194575496688641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
3.522 × 10¹⁰⁴(105-digit number)
35228547067817539713…34340389150993377281
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:57,731,307 XPM·at block #6,810,900 · updates every 60s
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