Block #2,826,922

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 9/6/2018, 6:59:42 AM · Difficulty 11.7101 · 4,012,088 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
f8bd9d1f46fd252ef43083aa0c1a89ef6383a34e85c7218704bd9b7df47b96dd

Height

#2,826,922

Difficulty

11.710134

Transactions

3

Size

801 B

Version

2

Bits

0bb5cb57

Nonce

934,295,532

Timestamp

9/6/2018, 6:59:42 AM

Confirmations

4,012,088

Merkle Root

da3580f071e4b241dddab7a6872679bd21870b43637d3cf1f38050f7aa0f8ccc
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.

6.867 × 10⁹⁴(95-digit number)
68672541402099229001…65895234290216003281
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
6.867 × 10⁹⁴(95-digit number)
68672541402099229001…65895234290216003281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.373 × 10⁹⁵(96-digit number)
13734508280419845800…31790468580432006561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
2.746 × 10⁹⁵(96-digit number)
27469016560839691600…63580937160864013121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
5.493 × 10⁹⁵(96-digit number)
54938033121679383201…27161874321728026241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
1.098 × 10⁹⁶(97-digit number)
10987606624335876640…54323748643456052481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
2.197 × 10⁹⁶(97-digit number)
21975213248671753280…08647497286912104961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
4.395 × 10⁹⁶(97-digit number)
43950426497343506560…17294994573824209921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
8.790 × 10⁹⁶(97-digit number)
87900852994687013121…34589989147648419841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.758 × 10⁹⁷(98-digit number)
17580170598937402624…69179978295296839681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
3.516 × 10⁹⁷(98-digit number)
35160341197874805248…38359956590593679361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
7.032 × 10⁹⁷(98-digit number)
70320682395749610497…76719913181187358721
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:57,956,347 XPM·at block #6,839,009 · updates every 60s
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