Home/Chain Registry/Block #922,420

Block #922,420

2CCLength 10★★☆☆☆

Cunningham Chain of the Second Kind · Discovered 2/4/2015, 11:20:41 AM · Difficulty 10.9154 · 5,875,970 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
743030815ec82a5dbce86070a2981281deeb01533037fb853d2f0a43234864fa

Height

#922,420

Difficulty

10.915426

Transactions

6

Size

127.02 KB

Version

2

Bits

0aea595e

Nonce

382,145,754

Timestamp

2/4/2015, 11:20:41 AM

Confirmations

5,875,970

Merkle Root

7483eaecaf8d79717cf9a4d8ab660245da06a9cea5879086e1890c9f4ce84f70
Transactions (6)
1 in → 1 out9.8800 XPM116 B
200 in → 1 out1078.2809 XPM28.94 KB
76 in → 1 out319.6144 XPM11.04 KB
200 in → 1 out1076.1482 XPM28.95 KB
200 in → 1 out1060.6457 XPM28.95 KB
200 in → 1 out960.1391 XPM28.95 KB
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.

1.058 × 10⁹⁶(97-digit number)
10584422417470598374…33756720791985562120
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
1.058 × 10⁹⁶(97-digit number)
10584422417470598374…33756720791985562121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
2.116 × 10⁹⁶(97-digit number)
21168844834941196748…67513441583971124241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
4.233 × 10⁹⁶(97-digit number)
42337689669882393496…35026883167942248481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
8.467 × 10⁹⁶(97-digit number)
84675379339764786993…70053766335884496961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
1.693 × 10⁹⁷(98-digit number)
16935075867952957398…40107532671768993921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
3.387 × 10⁹⁷(98-digit number)
33870151735905914797…80215065343537987841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
6.774 × 10⁹⁷(98-digit number)
67740303471811829595…60430130687075975681
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
1.354 × 10⁹⁸(99-digit number)
13548060694362365919…20860261374151951361
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
2.709 × 10⁹⁸(99-digit number)
27096121388724731838…41720522748303902721
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
5.419 × 10⁹⁸(99-digit number)
54192242777449463676…83441045496607805441
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.

View full Prime Chain Discovery page →
★★☆☆☆
Rarity
UncommonChain length 10
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, …
Verify on a Primecoin Node

Anyone running a Primecoin node can independently verify this block using the following RPC commands. Run these from the primecoin-cli command line or via the debug console in the Primecoin wallet.

1. Get block hash by height
getblockhash 922420

Returns the block hash for a given block height. Use this to confirm the hash shown above matches the chain.

2. Get full block data
getblock 743030815ec82a5dbce86070a2981281deeb01533037fb853d2f0a43234864fa

Returns the full block header including difficulty, prime chain origin, prime chain type, transaction IDs, and all other fields shown on this page.

How to run these commands: To verify this data independently, open a terminal on your own Primecoin node and run primecoin-cli <command>. Alternatively, open the Primecoin-Qt wallet, go to Help → Debug Window → Console, and type the command directly. The node must be fully synced to this block height for the commands to return results.

Cross-reference on Chainz Explorer

Chainz is an independent Primecoin block explorer. Compare this block's data to verify accuracy.

View Block #922,420 on Chainz ↗
Circulating Supply:57,631,128 XPM·at block #6,798,389 · updates every 60s
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