Block #2,791,101

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 8/12/2018, 7:04:42 PM · Difficulty 11.6758 · 4,051,360 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
440e8188db9ff17dd326cf33c901d49b38c22af6708182e896d4807adf6c0f0c

Height

#2,791,101

Difficulty

11.675825

Transactions

2

Size

426 B

Version

2

Bits

0bad02db

Nonce

606,440,067

Timestamp

8/12/2018, 7:04:42 PM

Confirmations

4,051,360

Merkle Root

f254d7d1f7b114ae194b405e733c325d454a9e08ff561ab2cbea73dd6ebcfe14
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.

2.906 × 10⁹⁷(98-digit number)
29064983493665484963…19955602973085286401
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
2.906 × 10⁹⁷(98-digit number)
29064983493665484963…19955602973085286401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
5.812 × 10⁹⁷(98-digit number)
58129966987330969927…39911205946170572801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
1.162 × 10⁹⁸(99-digit number)
11625993397466193985…79822411892341145601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
2.325 × 10⁹⁸(99-digit number)
23251986794932387971…59644823784682291201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
4.650 × 10⁹⁸(99-digit number)
46503973589864775942…19289647569364582401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
9.300 × 10⁹⁸(99-digit number)
93007947179729551884…38579295138729164801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
1.860 × 10⁹⁹(100-digit number)
18601589435945910376…77158590277458329601
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
3.720 × 10⁹⁹(100-digit number)
37203178871891820753…54317180554916659201
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
7.440 × 10⁹⁹(100-digit number)
74406357743783641507…08634361109833318401
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
1.488 × 10¹⁰⁰(101-digit number)
14881271548756728301…17268722219666636801
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
2.976 × 10¹⁰⁰(101-digit number)
29762543097513456602…34537444439333273601
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:57,984,105 XPM·at block #6,842,460 · updates every 60s
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