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Block #1,989,240

1CCLength 10β˜…β˜…β˜†β˜†β˜†

Cunningham Chain of the First Kind Β· Discovered 2/19/2017, 12:00:01 AM Β· Difficulty 10.7363 Β· 4,854,642 confirmations

1CC
Cunningham Chain of the First Kind

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

Block Header
Block Hash
fd0a928ba804687691e349a859f9af68c44063cbc32b3390bbb04fc523dd320a
View on Chainz β†—

Difficulty

10.736257

Transactions

1

Size

201 B

Version

2

Bits

0abc7b5a

Nonce

144,751,247

Timestamp

2/19/2017, 12:00:01 AM

Confirmations

4,854,642

Merkle Root

5c15be758e899eb79c6f3de046b932da2a37c8c1faab77ef96d3224d4484c128
Transactions (1)
Coinbase5c15be758e899e…d3224d4484c128
1 in β†’ 1 out8.6600 XPM110 B
ALcWaCYh…aF4dZzpw
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.

1.895 Γ— 10⁹⁢(97-digit number)
18958563613099803573…17630800581306644480
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
1.895 Γ— 10⁹⁢(97-digit number)
18958563613099803573…17630800581306644479
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
2
2^1 Γ— origin βˆ’ 1
3.791 Γ— 10⁹⁢(97-digit number)
37917127226199607147…35261601162613288959
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
3
2^2 Γ— origin βˆ’ 1
7.583 Γ— 10⁹⁢(97-digit number)
75834254452399214295…70523202325226577919
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
4
2^3 Γ— origin βˆ’ 1
1.516 Γ— 10⁹⁷(98-digit number)
15166850890479842859…41046404650453155839
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
5
2^4 Γ— origin βˆ’ 1
3.033 Γ— 10⁹⁷(98-digit number)
30333701780959685718…82092809300906311679
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
6
2^5 Γ— origin βˆ’ 1
6.066 Γ— 10⁹⁷(98-digit number)
60667403561919371436…64185618601812623359
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
7
2^6 Γ— origin βˆ’ 1
1.213 Γ— 10⁹⁸(99-digit number)
12133480712383874287…28371237203625246719
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
8
2^7 Γ— origin βˆ’ 1
2.426 Γ— 10⁹⁸(99-digit number)
24266961424767748574…56742474407250493439
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
9
2^8 Γ— origin βˆ’ 1
4.853 Γ— 10⁹⁸(99-digit number)
48533922849535497149…13484948814500986879
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2+1 β†’
10
2^9 Γ— origin βˆ’ 1
9.706 Γ— 10⁹⁸(99-digit number)
97067845699070994298…26969897629001973759
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 1989240

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 fd0a928ba804687691e349a859f9af68c44063cbc32b3390bbb04fc523dd320a

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 #1,989,240 on Chainz β†—
Circulating Supply:57,995,428 XPMΒ·at block #6,843,881 Β· updates every 60s
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