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Home/Chain Registry/Block #1,260,987

Block #1,260,987

2CCLength 10β˜…β˜…β˜†β˜†β˜†

Cunningham Chain of the Second Kind Β· Discovered 9/30/2015, 12:16:34 PM Β· Difficulty 10.8215 Β· 5,539,085 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
10dcfbefae6661535399b9f810a935fc4fd4cc70e173ece2d910ca8c0f79dd13
View on Chainz β†—

Difficulty

10.821465

Transactions

1

Size

207 B

Version

2

Bits

0ad24b8a

Nonce

1,190,936,460

Timestamp

9/30/2015, 12:16:34 PM

Confirmations

5,539,085

Merkle Root

df311097dfc040c6031919f46d4ed688f2d97ef3b5972196ca9cb90d53718661
Transactions (1)
Coinbasedf311097dfc040…9cb90d53718661
1 in β†’ 1 out8.5300 XPM116 B
AJCEY9yy…tg97E6zm
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.

8.470 Γ— 10⁹⁷(98-digit number)
84702167037716860914…08965906000755159040
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
8.470 Γ— 10⁹⁷(98-digit number)
84702167037716860914…08965906000755159041
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
2
2^1 Γ— origin + 1
1.694 Γ— 10⁹⁸(99-digit number)
16940433407543372182…17931812001510318081
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
3
2^2 Γ— origin + 1
3.388 Γ— 10⁹⁸(99-digit number)
33880866815086744365…35863624003020636161
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
4
2^3 Γ— origin + 1
6.776 Γ— 10⁹⁸(99-digit number)
67761733630173488731…71727248006041272321
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
5
2^4 Γ— origin + 1
1.355 Γ— 10⁹⁹(100-digit number)
13552346726034697746…43454496012082544641
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
6
2^5 Γ— origin + 1
2.710 Γ— 10⁹⁹(100-digit number)
27104693452069395492…86908992024165089281
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
7
2^6 Γ— origin + 1
5.420 Γ— 10⁹⁹(100-digit number)
54209386904138790985…73817984048330178561
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
8
2^7 Γ— origin + 1
1.084 Γ— 10¹⁰⁰(101-digit number)
10841877380827758197…47635968096660357121
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
9
2^8 Γ— origin + 1
2.168 Γ— 10¹⁰⁰(101-digit number)
21683754761655516394…95271936193320714241
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
10
2^9 Γ— origin + 1
4.336 Γ— 10¹⁰⁰(101-digit number)
43367509523311032788…90543872386641428481
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 1260987

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 10dcfbefae6661535399b9f810a935fc4fd4cc70e173ece2d910ca8c0f79dd13

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 #1,260,987 on Chainz β†—
Circulating Supply:57,644,640 XPMΒ·at block #6,800,071 Β· updates every 60s
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