Block #271,044

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 11/24/2013, 9:29:19 AM · Difficulty 9.9515 · 6,533,904 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
b5a97877080d44aeeccd5b4a44b3360ee61ad4d60ce3b45e644563f50ba6fc0d

Height

#271,044

Difficulty

9.951473

Transactions

7

Size

3.13 KB

Version

2

Bits

09f393ba

Nonce

39,209

Timestamp

11/24/2013, 9:29:19 AM

Confirmations

6,533,904

Merkle Root

27c0fb052a9183bba309ca6e1b543dc07474033642676a1f198e98691bdddb70
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.

9.289 × 10¹⁰⁴(105-digit number)
92894832894524133659…36309153290225986561
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
9.289 × 10¹⁰⁴(105-digit number)
92894832894524133659…36309153290225986561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.857 × 10¹⁰⁵(106-digit number)
18578966578904826731…72618306580451973121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
3.715 × 10¹⁰⁵(106-digit number)
37157933157809653463…45236613160903946241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
7.431 × 10¹⁰⁵(106-digit number)
74315866315619306927…90473226321807892481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
1.486 × 10¹⁰⁶(107-digit number)
14863173263123861385…80946452643615784961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
2.972 × 10¹⁰⁶(107-digit number)
29726346526247722771…61892905287231569921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
5.945 × 10¹⁰⁶(107-digit number)
59452693052495445542…23785810574463139841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.189 × 10¹⁰⁷(108-digit number)
11890538610499089108…47571621148926279681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
2.378 × 10¹⁰⁷(108-digit number)
23781077220998178216…95143242297852559361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
4.756 × 10¹⁰⁷(108-digit number)
47562154441996356433…90286484595705118721
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:57,683,649 XPM·at block #6,804,947 · updates every 60s
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