Block #2,695,998

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 6/7/2018, 6:37:07 PM · Difficulty 11.6705 · 4,144,052 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
19a7cbf14840ca7e1e63ca2dea5141ca7c1b046855c96f945c25fef73dc2786e

Height

#2,695,998

Difficulty

11.670468

Transactions

7

Size

2.00 KB

Version

2

Bits

0baba3ca

Nonce

1,723,376,366

Timestamp

6/7/2018, 6:37:07 PM

Confirmations

4,144,052

Merkle Root

8615ca45d167ce0c3dc0c1171267397dda3fe41070c890581f91642afa56051b
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.

1.375 × 10⁹⁶(97-digit number)
13754152922189221710…46602292117808793601
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
1.375 × 10⁹⁶(97-digit number)
13754152922189221710…46602292117808793601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
2.750 × 10⁹⁶(97-digit number)
27508305844378443420…93204584235617587201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
5.501 × 10⁹⁶(97-digit number)
55016611688756886841…86409168471235174401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.100 × 10⁹⁷(98-digit number)
11003322337751377368…72818336942470348801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
2.200 × 10⁹⁷(98-digit number)
22006644675502754736…45636673884940697601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
4.401 × 10⁹⁷(98-digit number)
44013289351005509473…91273347769881395201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
8.802 × 10⁹⁷(98-digit number)
88026578702011018946…82546695539762790401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.760 × 10⁹⁸(99-digit number)
17605315740402203789…65093391079525580801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
3.521 × 10⁹⁸(99-digit number)
35210631480804407578…30186782159051161601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
7.042 × 10⁹⁸(99-digit number)
70421262961608815157…60373564318102323201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
1.408 × 10⁹⁹(100-digit number)
14084252592321763031…20747128636204646401
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:57,964,708 XPM·at block #6,840,049 · updates every 60s
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