Block #2,829,469

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 9/8/2018, 12:37:26 AM · Difficulty 11.7131 · 4,008,947 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
9c6ab80e12883c6badf6b76165b234369a927db26ba4fac7a5c208b45280f50d

Height

#2,829,469

Difficulty

11.713105

Transactions

9

Size

3.35 KB

Version

2

Bits

0bb68e0d

Nonce

1,499,297,550

Timestamp

9/8/2018, 12:37:26 AM

Confirmations

4,008,947

Merkle Root

3394c731a756c2948184a948e27b4ae5ea51937877188e415412033787dd43b5
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.

7.821 × 10⁹⁷(98-digit number)
78216553478467348223…27584574862271692801
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
7.821 × 10⁹⁷(98-digit number)
78216553478467348223…27584574862271692801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.564 × 10⁹⁸(99-digit number)
15643310695693469644…55169149724543385601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
3.128 × 10⁹⁸(99-digit number)
31286621391386939289…10338299449086771201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
6.257 × 10⁹⁸(99-digit number)
62573242782773878578…20676598898173542401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
1.251 × 10⁹⁹(100-digit number)
12514648556554775715…41353197796347084801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
2.502 × 10⁹⁹(100-digit number)
25029297113109551431…82706395592694169601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
5.005 × 10⁹⁹(100-digit number)
50058594226219102862…65412791185388339201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.001 × 10¹⁰⁰(101-digit number)
10011718845243820572…30825582370776678401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
2.002 × 10¹⁰⁰(101-digit number)
20023437690487641145…61651164741553356801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
4.004 × 10¹⁰⁰(101-digit number)
40046875380975282290…23302329483106713601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
8.009 × 10¹⁰⁰(101-digit number)
80093750761950564580…46604658966213427201
Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 11 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
RareChain length 11

Approximately 1 in 1,000 blocks. Noteworthy discoveries.

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:57,951,601 XPM·at block #6,838,415 · updates every 60s
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