Block #2,795,213

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 8/15/2018, 2:41:52 PM · Difficulty 11.6794 · 4,047,493 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
28a270a16c535c2176a9295c70f74a9d3215c8d1742d6b54d34b8e5a66134a6c

Height

#2,795,213

Difficulty

11.679441

Transactions

34

Size

9.50 KB

Version

2

Bits

0badefd6

Nonce

201,454,810

Timestamp

8/15/2018, 2:41:52 PM

Confirmations

4,047,493

Merkle Root

8d5e46378ee6ad624d72fb64d9cfdfb7f75eeeebe30e64578c0ef22db26560d9
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.

2.119 × 10⁹⁴(95-digit number)
21193134850593675523…09696364029098494801
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
2.119 × 10⁹⁴(95-digit number)
21193134850593675523…09696364029098494801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
4.238 × 10⁹⁴(95-digit number)
42386269701187351047…19392728058196989601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
8.477 × 10⁹⁴(95-digit number)
84772539402374702095…38785456116393979201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.695 × 10⁹⁵(96-digit number)
16954507880474940419…77570912232787958401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
3.390 × 10⁹⁵(96-digit number)
33909015760949880838…55141824465575916801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
6.781 × 10⁹⁵(96-digit number)
67818031521899761676…10283648931151833601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
1.356 × 10⁹⁶(97-digit number)
13563606304379952335…20567297862303667201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
2.712 × 10⁹⁶(97-digit number)
27127212608759904670…41134595724607334401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
5.425 × 10⁹⁶(97-digit number)
54254425217519809341…82269191449214668801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
1.085 × 10⁹⁷(98-digit number)
10850885043503961868…64538382898429337601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
2.170 × 10⁹⁷(98-digit number)
21701770087007923736…29076765796858675201
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:57,985,998 XPM·at block #6,842,705 · updates every 60s
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