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Home/Chain Registry/Block #1,273,442

Block #1,273,442

2CCLength 10β˜…β˜…β˜†β˜†β˜†

Cunningham Chain of the Second Kind Β· Discovered 10/9/2015, 2:51:13 AM Β· Difficulty 10.8240 Β· 5,568,170 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
ef67545fefafa2ee4c8690cd8b904eac4ebe2acda00d66506776842342df93ef
View on Chainz β†—

Difficulty

10.824008

Transactions

1

Size

242 B

Version

2

Bits

0ad2f235

Nonce

54,023,606

Timestamp

10/9/2015, 2:51:13 AM

Confirmations

5,568,170

Merkle Root

8f58b94582c07f5f682be18288421c4a3bcd96813a684f9e8cbb44b28d519f06
Transactions (1)
Coinbase8f58b94582c07f…bb44b28d519f06
1 in β†’ 2 out8.5200 XPM152 B
AW7XpJLz…npEJgCfvALPu3s2c…EJXLjVFh
Prime Chain Origin

This is the prime chain origin stored in the block header. It is a composite number (not prime itself) β€” it equals the first prime in the chain multiplied by a primorial. The origin anchors the entire chain to this specific block.

6.414 Γ— 10⁹⁡(96-digit number)
64140692162010412254…73340585307205701340
Discovered Prime Numbers
p_k = 2^k Γ— 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
6.414 Γ— 10⁹⁡(96-digit number)
64140692162010412254…73340585307205701341
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
2
2^1 Γ— origin + 1
1.282 Γ— 10⁹⁢(97-digit number)
12828138432402082450…46681170614411402681
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
3
2^2 Γ— origin + 1
2.565 Γ— 10⁹⁢(97-digit number)
25656276864804164901…93362341228822805361
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
4
2^3 Γ— origin + 1
5.131 Γ— 10⁹⁢(97-digit number)
51312553729608329803…86724682457645610721
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
5
2^4 Γ— origin + 1
1.026 Γ— 10⁹⁷(98-digit number)
10262510745921665960…73449364915291221441
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
6
2^5 Γ— origin + 1
2.052 Γ— 10⁹⁷(98-digit number)
20525021491843331921…46898729830582442881
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
7
2^6 Γ— origin + 1
4.105 Γ— 10⁹⁷(98-digit number)
41050042983686663842…93797459661164885761
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
8
2^7 Γ— origin + 1
8.210 Γ— 10⁹⁷(98-digit number)
82100085967373327685…87594919322329771521
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
9
2^8 Γ— origin + 1
1.642 Γ— 10⁹⁸(99-digit number)
16420017193474665537…75189838644659543041
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
10
2^9 Γ— origin + 1
3.284 Γ— 10⁹⁸(99-digit number)
32840034386949331074…50379677289319086081
Verify on FactorDB β†—Wolfram Alpha β†—

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 β€” the large number shown above β€” 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 β†’
β˜…β˜…β˜†β˜†β˜†
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 Γ— 3 Γ— 5 Γ— 7 Γ— …), the result is the first prime in the chain. The origin is deliberately divisible by this primorial β€” that divisibility is part of the proof.

Prime Chain Origin = First Prime Γ— Primorial (2Β·3Β·5Β·7Β·11·…)
Source: Primecoin prime.cpp β€” CheckPrimeProofOfWork()

This is why the origin has many small prime factors β€” those factors are the primorial divisor. The chain then extends from the first prime using the 2CC formula:

2CC: p₁ (first prime), pβ‚‚ = 2p₁ βˆ’ 1, p₃ = 2pβ‚‚ βˆ’ 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 1273442

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 ef67545fefafa2ee4c8690cd8b904eac4ebe2acda00d66506776842342df93ef

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 β†’ Debug Window β†’ 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 #1,273,442 on Chainz β†—
Circulating Supply:57,977,277 XPMΒ·at block #6,841,611 Β· updates every 60s
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