Block #232,767

2CCLength 9★☆☆☆☆

Cunningham Chain of the Second Kind · Discovered 10/29/2013, 7:59:29 AM · Difficulty 9.9414 · 6,570,545 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
b776ce75ccb7a88b6a73d5cbd718657eeb83f9017cdb9c392994eabb41b9054c

Height

#232,767

Difficulty

9.941383

Transactions

7

Size

2.67 KB

Version

2

Bits

09f0fe77

Nonce

63,107

Timestamp

10/29/2013, 7:59:29 AM

Confirmations

6,570,545

Merkle Root

4e8d1878ded8da03d0fc979a8b76a13b76b15b6c71ff871cce6436bd78cfb0e2
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.

7.577 × 10⁹²(93-digit number)
75776598770953955303…44319248885902954401
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
7.577 × 10⁹²(93-digit number)
75776598770953955303…44319248885902954401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.515 × 10⁹³(94-digit number)
15155319754190791060…88638497771805908801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
3.031 × 10⁹³(94-digit number)
30310639508381582121…77276995543611817601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
6.062 × 10⁹³(94-digit number)
60621279016763164243…54553991087223635201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
1.212 × 10⁹⁴(95-digit number)
12124255803352632848…09107982174447270401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
2.424 × 10⁹⁴(95-digit number)
24248511606705265697…18215964348894540801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
4.849 × 10⁹⁴(95-digit number)
48497023213410531394…36431928697789081601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
9.699 × 10⁹⁴(95-digit number)
96994046426821062789…72863857395578163201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.939 × 10⁹⁵(96-digit number)
19398809285364212557…45727714791156326401
Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 9 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
CommonChain length 9

Found in most blocks. The baseline for Primecoin's proof-of-work.

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:57,670,524 XPM·at block #6,803,311 · updates every 60s
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