Block #2,814,866

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 8/29/2018, 5:38:42 AM · Difficulty 11.6823 · 4,026,597 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
a9992aca5aaa8c0a7d93bea6df175488c1c90c0787e4c1a4b10fb84068ffae41

Height

#2,814,866

Difficulty

11.682324

Transactions

21

Size

5.94 KB

Version

2

Bits

0baeacc8

Nonce

1,176,683,749

Timestamp

8/29/2018, 5:38:42 AM

Confirmations

4,026,597

Merkle Root

b2755b13856f4b91a17fac8249d119e601b2e7a16785a1a4c11aa1eb302566f9
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.

1.579 × 10⁹¹(92-digit number)
15796236890668859217…15079041633622316881
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
1.579 × 10⁹¹(92-digit number)
15796236890668859217…15079041633622316881
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
3.159 × 10⁹¹(92-digit number)
31592473781337718435…30158083267244633761
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
6.318 × 10⁹¹(92-digit number)
63184947562675436870…60316166534489267521
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.263 × 10⁹²(93-digit number)
12636989512535087374…20632333068978535041
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
2.527 × 10⁹²(93-digit number)
25273979025070174748…41264666137957070081
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
5.054 × 10⁹²(93-digit number)
50547958050140349496…82529332275914140161
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
1.010 × 10⁹³(94-digit number)
10109591610028069899…65058664551828280321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
2.021 × 10⁹³(94-digit number)
20219183220056139798…30117329103656560641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
4.043 × 10⁹³(94-digit number)
40438366440112279597…60234658207313121281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
8.087 × 10⁹³(94-digit number)
80876732880224559194…20469316414626242561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
1.617 × 10⁹⁴(95-digit number)
16175346576044911838…40938632829252485121
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:57,976,077 XPM·at block #6,841,462 · updates every 60s
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