Block #3,626,579

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 4/2/2020, 9:12:30 PM · Difficulty 10.9085 · 3,211,796 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
bb1fa1c808db95b614c97211ceb58b52ef5d9105d1e0b6355c8f4a4a06eb8413

Height

#3,626,579

Difficulty

10.908532

Transactions

2

Size

3.02 KB

Version

2

Bits

0ae89586

Nonce

1,612,868,125

Timestamp

4/2/2020, 9:12:30 PM

Confirmations

3,211,796

Merkle Root

be868a7d669f170c08a3ca2bbda4abcb521676f96e98079682941cb2e2674638
Transactions (2)
1 in → 1 out8.4300 XPM110 B
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.

1.587 × 10⁹⁷(98-digit number)
15878854797694851775…64857583704149852161
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
1.587 × 10⁹⁷(98-digit number)
15878854797694851775…64857583704149852161
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
3.175 × 10⁹⁷(98-digit number)
31757709595389703551…29715167408299704321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
6.351 × 10⁹⁷(98-digit number)
63515419190779407102…59430334816599408641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.270 × 10⁹⁸(99-digit number)
12703083838155881420…18860669633198817281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
2.540 × 10⁹⁸(99-digit number)
25406167676311762840…37721339266397634561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
5.081 × 10⁹⁸(99-digit number)
50812335352623525681…75442678532795269121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
1.016 × 10⁹⁹(100-digit number)
10162467070524705136…50885357065590538241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
2.032 × 10⁹⁹(100-digit number)
20324934141049410272…01770714131181076481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
4.064 × 10⁹⁹(100-digit number)
40649868282098820545…03541428262362152961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
8.129 × 10⁹⁹(100-digit number)
81299736564197641090…07082856524724305921
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:57,951,270 XPM·at block #6,838,374 · updates every 60s
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