Block #2,110,685

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 5/10/2017, 10:31:13 PM · Difficulty 10.9032 · 4,731,864 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
159656438e46e02f5a231b61ab14c36c543f02ee38bb60f0c698cb2076d61af3

Height

#2,110,685

Difficulty

10.903155

Transactions

2

Size

425 B

Version

2

Bits

0ae73526

Nonce

1,693,982,143

Timestamp

5/10/2017, 10:31:13 PM

Confirmations

4,731,864

Merkle Root

4e0b1f383a3e4c132719b8170c3d0e2c8a7db9ac59eafd9b1e5504b8df18d1b4
Transactions (2)
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.

1.537 × 10⁹⁴(95-digit number)
15377785972521453597…61125423422549467201
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
1.537 × 10⁹⁴(95-digit number)
15377785972521453597…61125423422549467201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
3.075 × 10⁹⁴(95-digit number)
30755571945042907194…22250846845098934401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
6.151 × 10⁹⁴(95-digit number)
61511143890085814388…44501693690197868801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.230 × 10⁹⁵(96-digit number)
12302228778017162877…89003387380395737601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
2.460 × 10⁹⁵(96-digit number)
24604457556034325755…78006774760791475201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
4.920 × 10⁹⁵(96-digit number)
49208915112068651511…56013549521582950401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
9.841 × 10⁹⁵(96-digit number)
98417830224137303022…12027099043165900801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.968 × 10⁹⁶(97-digit number)
19683566044827460604…24054198086331801601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
3.936 × 10⁹⁶(97-digit number)
39367132089654921208…48108396172663603201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
7.873 × 10⁹⁶(97-digit number)
78734264179309842417…96216792345327206401
Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 10 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
UncommonChain length 10

Roughly 1 in 100 blocks. Solid but expected in a healthy network.

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:57,984,817 XPM·at block #6,842,548 · updates every 60s
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