Block #2,932,685

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 11/21/2018, 7:42:50 AM · Difficulty 11.3999 · 3,908,801 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
3cba2390fbcca1d92ac758ebdbf2fd8ba0668fa715a601364983bafc471d40a1

Height

#2,932,685

Difficulty

11.399904

Transactions

3

Size

2.11 KB

Version

2

Bits

0b666020

Nonce

273,004,033

Timestamp

11/21/2018, 7:42:50 AM

Confirmations

3,908,801

Merkle Root

1564dd3dc9ba4fd8bbcb663c876844e61e1f2ba6456fe0455e2ec5ecbd2527c1
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.

1.357 × 10⁹⁶(97-digit number)
13574201771988613426…27062587136342357121
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
1.357 × 10⁹⁶(97-digit number)
13574201771988613426…27062587136342357121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
2.714 × 10⁹⁶(97-digit number)
27148403543977226852…54125174272684714241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
5.429 × 10⁹⁶(97-digit number)
54296807087954453705…08250348545369428481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.085 × 10⁹⁷(98-digit number)
10859361417590890741…16500697090738856961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
2.171 × 10⁹⁷(98-digit number)
21718722835181781482…33001394181477713921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
4.343 × 10⁹⁷(98-digit number)
43437445670363562964…66002788362955427841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
8.687 × 10⁹⁷(98-digit number)
86874891340727125928…32005576725910855681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.737 × 10⁹⁸(99-digit number)
17374978268145425185…64011153451821711361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
3.474 × 10⁹⁸(99-digit number)
34749956536290850371…28022306903643422721
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
6.949 × 10⁹⁸(99-digit number)
69499913072581700742…56044613807286845441
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
1.389 × 10⁹⁹(100-digit number)
13899982614516340148…12089227614573690881
Verify on FactorDB ↗Wolfram Alpha ↗

What this block proved

The miner who found this block proved the existence of 11 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
RareChain length 11

Approximately 1 in 1,000 blocks. Noteworthy discoveries.

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:57,976,263 XPM·at block #6,841,485 · updates every 60s
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