Block #2,796,304

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 8/16/2018, 8:22:48 AM · Difficulty 11.6813 · 4,045,139 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
4426ffac786f5eaf67c82f7d623e3974b47d828b3466e388c11d88b1104dbb21

Height

#2,796,304

Difficulty

11.681278

Transactions

7

Size

3.19 KB

Version

2

Bits

0bae6844

Nonce

891,612,617

Timestamp

8/16/2018, 8:22:48 AM

Confirmations

4,045,139

Merkle Root

d4e8ce14e182617253e64a4808e0e6e2a99ca92193900065e66ea4b871d9d0aa
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.

8.521 × 10⁹³(94-digit number)
85211050094613675266…16623386276718726201
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
8.521 × 10⁹³(94-digit number)
85211050094613675266…16623386276718726201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.704 × 10⁹⁴(95-digit number)
17042210018922735053…33246772553437452401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
3.408 × 10⁹⁴(95-digit number)
34084420037845470106…66493545106874904801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
6.816 × 10⁹⁴(95-digit number)
68168840075690940213…32987090213749809601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
1.363 × 10⁹⁵(96-digit number)
13633768015138188042…65974180427499619201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
2.726 × 10⁹⁵(96-digit number)
27267536030276376085…31948360854999238401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
5.453 × 10⁹⁵(96-digit number)
54535072060552752170…63896721709998476801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.090 × 10⁹⁶(97-digit number)
10907014412110550434…27793443419996953601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
2.181 × 10⁹⁶(97-digit number)
21814028824221100868…55586886839993907201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
4.362 × 10⁹⁶(97-digit number)
43628057648442201736…11173773679987814401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
8.725 × 10⁹⁶(97-digit number)
87256115296884403473…22347547359975628801
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:57,975,924 XPM·at block #6,841,442 · updates every 60s
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