Block #368,384

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 1/20/2014, 4:58:37 PM · Difficulty 10.4411 · 6,447,878 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
eb72d7bf3686cec88d0c22754d993ea39c25da571d4360962b0333c1025b03b3

Height

#368,384

Difficulty

10.441067

Transactions

1

Size

1.01 KB

Version

2

Bits

0a70e9cc

Nonce

133,274

Timestamp

1/20/2014, 4:58:37 PM

Confirmations

6,447,878

Merkle Root

15f21e037c693ea5c470c1d7d375df50bc0c5189e76556f7255057d09d9d39e2
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.

4.961 × 10⁹³(94-digit number)
49613897025295253247…05204799131526874561
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
4.961 × 10⁹³(94-digit number)
49613897025295253247…05204799131526874561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
9.922 × 10⁹³(94-digit number)
99227794050590506494…10409598263053749121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
1.984 × 10⁹⁴(95-digit number)
19845558810118101298…20819196526107498241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
3.969 × 10⁹⁴(95-digit number)
39691117620236202597…41638393052214996481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
7.938 × 10⁹⁴(95-digit number)
79382235240472405195…83276786104429992961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
1.587 × 10⁹⁵(96-digit number)
15876447048094481039…66553572208859985921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
3.175 × 10⁹⁵(96-digit number)
31752894096188962078…33107144417719971841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
6.350 × 10⁹⁵(96-digit number)
63505788192377924156…66214288835439943681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.270 × 10⁹⁶(97-digit number)
12701157638475584831…32428577670879887361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
2.540 × 10⁹⁶(97-digit number)
25402315276951169662…64857155341759774721
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:57,774,209 XPM·at block #6,816,261 · updates every 60s
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