Block #3,031,722

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 1/30/2019, 2:29:01 PM · Difficulty 11.0830 · 3,810,741 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
8e8fd6be35a17b3433cb5db776c297de9658e693099c2f266cd8b0289f80a3ff

Height

#3,031,722

Difficulty

11.082996

Transactions

5

Size

2.60 KB

Version

2

Bits

0b153f3b

Nonce

630,824,761

Timestamp

1/30/2019, 2:29:01 PM

Confirmations

3,810,741

Merkle Root

62149bdf60f15dc3310c7d798117a8081dba682b09fd4c115b4e4ca30c0df6e2
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.

2.001 × 10⁹⁴(95-digit number)
20019625659228016079…04713688329512094341
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
2.001 × 10⁹⁴(95-digit number)
20019625659228016079…04713688329512094341
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
4.003 × 10⁹⁴(95-digit number)
40039251318456032159…09427376659024188681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
8.007 × 10⁹⁴(95-digit number)
80078502636912064318…18854753318048377361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.601 × 10⁹⁵(96-digit number)
16015700527382412863…37709506636096754721
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
3.203 × 10⁹⁵(96-digit number)
32031401054764825727…75419013272193509441
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
6.406 × 10⁹⁵(96-digit number)
64062802109529651454…50838026544387018881
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
1.281 × 10⁹⁶(97-digit number)
12812560421905930290…01676053088774037761
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
2.562 × 10⁹⁶(97-digit number)
25625120843811860581…03352106177548075521
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
5.125 × 10⁹⁶(97-digit number)
51250241687623721163…06704212355096151041
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
1.025 × 10⁹⁷(98-digit number)
10250048337524744232…13408424710192302081
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
2.050 × 10⁹⁷(98-digit number)
20500096675049488465…26816849420384604161
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:57,984,122 XPM·at block #6,842,462 · updates every 60s
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