Block #680,079

2CCLength 12★★★★☆

Cunningham Chain of the Second Kind · Discovered 8/16/2014, 11:06:52 AM · Difficulty 10.9627 · 6,128,833 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
cf6a7564070508b2741bcfce0e774e562df48321f521754cd10cdc5615405b4e

Height

#680,079

Difficulty

10.962691

Transactions

8

Size

3.05 KB

Version

2

Bits

0af672ed

Nonce

489,351,855

Timestamp

8/16/2014, 11:06:52 AM

Confirmations

6,128,833

Merkle Root

589789b6525b684ff2ce8588e2b90e3cb0c9d6182297b50eeaf48e5ed219912b
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.

5.411 × 10⁹⁶(97-digit number)
54117653951439631128…50271005845599250041
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
5.411 × 10⁹⁶(97-digit number)
54117653951439631128…50271005845599250041
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.082 × 10⁹⁷(98-digit number)
10823530790287926225…00542011691198500081
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
2.164 × 10⁹⁷(98-digit number)
21647061580575852451…01084023382397000161
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
4.329 × 10⁹⁷(98-digit number)
43294123161151704903…02168046764794000321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
8.658 × 10⁹⁷(98-digit number)
86588246322303409806…04336093529588000641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
1.731 × 10⁹⁸(99-digit number)
17317649264460681961…08672187059176001281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
3.463 × 10⁹⁸(99-digit number)
34635298528921363922…17344374118352002561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
6.927 × 10⁹⁸(99-digit number)
69270597057842727844…34688748236704005121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.385 × 10⁹⁹(100-digit number)
13854119411568545568…69377496473408010241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
2.770 × 10⁹⁹(100-digit number)
27708238823137091137…38754992946816020481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
5.541 × 10⁹⁹(100-digit number)
55416477646274182275…77509985893632040961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
12
2^11 × origin + 1
1.108 × 10¹⁰⁰(101-digit number)
11083295529254836455…55019971787264081921
Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 12 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
ExceptionalChain length 12

Around 1 in 10,000 blocks. A significant mathematical achievement.

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:57,715,351 XPM·at block #6,808,911 · updates every 60s
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