Block #844,996

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 12/8/2014, 1:32:22 PM · Difficulty 10.9726 · 5,998,922 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
d5ba68ae73d9c693c9c650e7ad2c795350cf52e9dc6001d35298c314e4b4e202

Height

#844,996

Difficulty

10.972613

Transactions

3

Size

658 B

Version

2

Bits

0af8fd31

Nonce

830,464,226

Timestamp

12/8/2014, 1:32:22 PM

Confirmations

5,998,922

Merkle Root

20683fea468a8240a6fee668bb8798cb9c7bfb8d5485454152b8a2abc4595956
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.

1.334 × 10⁹⁸(99-digit number)
13340901151314490116…76751406746401658881
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
1.334 × 10⁹⁸(99-digit number)
13340901151314490116…76751406746401658881
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
2.668 × 10⁹⁸(99-digit number)
26681802302628980232…53502813492803317761
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
5.336 × 10⁹⁸(99-digit number)
53363604605257960465…07005626985606635521
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.067 × 10⁹⁹(100-digit number)
10672720921051592093…14011253971213271041
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
2.134 × 10⁹⁹(100-digit number)
21345441842103184186…28022507942426542081
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
4.269 × 10⁹⁹(100-digit number)
42690883684206368372…56045015884853084161
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
8.538 × 10⁹⁹(100-digit number)
85381767368412736744…12090031769706168321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.707 × 10¹⁰⁰(101-digit number)
17076353473682547348…24180063539412336641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
3.415 × 10¹⁰⁰(101-digit number)
34152706947365094697…48360127078824673281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
6.830 × 10¹⁰⁰(101-digit number)
68305413894730189395…96720254157649346561
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:57,995,715 XPM·at block #6,843,917 · updates every 60s
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