Block #2,112,307

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 5/12/2017, 3:01:05 AM · Difficulty 10.9015 · 4,718,559 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
18f1384abe345d21364d5e72993aecd10a23275e00ec5a58daf25ea9cbe3921e

Height

#2,112,307

Difficulty

10.901520

Transactions

2

Size

1.43 KB

Version

2

Bits

0ae6ca08

Nonce

467,126,380

Timestamp

5/12/2017, 3:01:05 AM

Confirmations

4,718,559

Merkle Root

9810fee098fe8bccc8dbaf4e736d1f8e7849b9dc5c5aac8525aeff03a13d56a3
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.

1.995 × 10⁹⁵(96-digit number)
19957275409130447205…40634898480488693761
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
1.995 × 10⁹⁵(96-digit number)
19957275409130447205…40634898480488693761
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
3.991 × 10⁹⁵(96-digit number)
39914550818260894410…81269796960977387521
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
7.982 × 10⁹⁵(96-digit number)
79829101636521788820…62539593921954775041
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.596 × 10⁹⁶(97-digit number)
15965820327304357764…25079187843909550081
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
3.193 × 10⁹⁶(97-digit number)
31931640654608715528…50158375687819100161
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
6.386 × 10⁹⁶(97-digit number)
63863281309217431056…00316751375638200321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
1.277 × 10⁹⁷(98-digit number)
12772656261843486211…00633502751276400641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
2.554 × 10⁹⁷(98-digit number)
25545312523686972422…01267005502552801281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
5.109 × 10⁹⁷(98-digit number)
51090625047373944845…02534011005105602561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
1.021 × 10⁹⁸(99-digit number)
10218125009474788969…05068022010211205121
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:57,891,066 XPM·at block #6,830,865 · updates every 60s
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