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Home/Chain Registry/Block #1,990,128

Block #1,990,128

1CCLength 10β˜…β˜…β˜†β˜†β˜†

Cunningham Chain of the First Kind Β· Discovered 2/19/2017, 3:02:38 PM Β· Difficulty 10.7355 Β· 4,834,881 confirmations

1CC
Cunningham Chain of the First Kind

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

Block Header
Block Hash
dac2d55eb574ab214f4e6207f238fd21195b78b367310be528987a5ea98b3935
View on Chainz β†—

Difficulty

10.735467

Transactions

1

Size

201 B

Version

2

Bits

0abc4792

Nonce

297,786,298

Timestamp

2/19/2017, 3:02:38 PM

Confirmations

4,834,881

Merkle Root

840d43338cfa8e400d2825e9df3c917dfe08f35f7c29663b22bab0b7b6b26477
Transactions (1)
Coinbase840d43338cfa8e…bab0b7b6b26477
1 in β†’ 1 out8.6600 XPM110 B
AQwKkRje…N9fa8ge8
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.

2.437 Γ— 10⁹⁢(97-digit number)
24372840840645672750…72394187185996072960
Discovered Prime Numbers
p_k = 2^k Γ— origin βˆ’ 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 βˆ’ 1
2.437 Γ— 10⁹⁢(97-digit number)
24372840840645672750…72394187185996072959
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
2
2^1 Γ— origin βˆ’ 1
4.874 Γ— 10⁹⁢(97-digit number)
48745681681291345500…44788374371992145919
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
3
2^2 Γ— origin βˆ’ 1
9.749 Γ— 10⁹⁢(97-digit number)
97491363362582691000…89576748743984291839
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
4
2^3 Γ— origin βˆ’ 1
1.949 Γ— 10⁹⁷(98-digit number)
19498272672516538200…79153497487968583679
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
5
2^4 Γ— origin βˆ’ 1
3.899 Γ— 10⁹⁷(98-digit number)
38996545345033076400…58306994975937167359
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
6
2^5 Γ— origin βˆ’ 1
7.799 Γ— 10⁹⁷(98-digit number)
77993090690066152800…16613989951874334719
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
7
2^6 Γ— origin βˆ’ 1
1.559 Γ— 10⁹⁸(99-digit number)
15598618138013230560…33227979903748669439
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
8
2^7 Γ— origin βˆ’ 1
3.119 Γ— 10⁹⁸(99-digit number)
31197236276026461120…66455959807497338879
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
9
2^8 Γ— origin βˆ’ 1
6.239 Γ— 10⁹⁸(99-digit number)
62394472552052922240…32911919614994677759
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
10
2^9 Γ— origin βˆ’ 1
1.247 Γ— 10⁹⁹(100-digit number)
12478894510410584448…65823839229989355519
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 First 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 1CC formula:

1CC: p₁ (first prime), pβ‚‚ = 2p₁ + 1, p₃ = 2pβ‚‚ + 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 1990128

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 dac2d55eb574ab214f4e6207f238fd21195b78b367310be528987a5ea98b3935

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 #1,990,128 on Chainz β†—
Circulating Supply:57,844,156 XPMΒ·at block #6,825,008 Β· updates every 60s
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