Block #244,517

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 11/4/2013, 10:12:29 PM · Difficulty 9.9630 · 6,546,461 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
70289598c535aa59db31c2ac4728698679327c2d01754c15d9238746d8383812

Height

#244,517

Difficulty

9.962995

Transactions

11

Size

2.58 KB

Version

2

Bits

09f686d7

Nonce

135,043

Timestamp

11/4/2013, 10:12:29 PM

Confirmations

6,546,461

Merkle Root

7fe99554ff6c90d417101c5b9dac9b1fc357b8c6ac2585cbeb7613e5c3ca9576
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.

3.597 × 10¹⁰¹(102-digit number)
35977365907694316236…88614474825946680321
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
3.597 × 10¹⁰¹(102-digit number)
35977365907694316236…88614474825946680321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
7.195 × 10¹⁰¹(102-digit number)
71954731815388632473…77228949651893360641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
1.439 × 10¹⁰²(103-digit number)
14390946363077726494…54457899303786721281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
2.878 × 10¹⁰²(103-digit number)
28781892726155452989…08915798607573442561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
5.756 × 10¹⁰²(103-digit number)
57563785452310905978…17831597215146885121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
1.151 × 10¹⁰³(104-digit number)
11512757090462181195…35663194430293770241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
2.302 × 10¹⁰³(104-digit number)
23025514180924362391…71326388860587540481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
4.605 × 10¹⁰³(104-digit number)
46051028361848724782…42652777721175080961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
9.210 × 10¹⁰³(104-digit number)
92102056723697449565…85305555442350161921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
1.842 × 10¹⁰⁴(105-digit number)
18420411344739489913…70611110884700323841
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:57,571,839 XPM·at block #6,790,977 · updates every 60s