XPM Prime Explorer symbol
XPMPrime Explorer

Block #1,365,489

2CCLength 11β˜…β˜…β˜…β˜†β˜†

Cunningham Chain of the Second Kind Β· Discovered 12/11/2015, 3:33:29 PM Β· Difficulty 10.8459 Β· 5,445,289 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
4a26549ff3025c257d8987a26bf0400b7b65a31846672f9368ac972d2c363a13
View on Chainz β†—

Height

#1,365,489

Difficulty

10.845870

Transactions

2

Size

572 B

Version

2

Bits

0ad88af0

Nonce

497,050,105

Timestamp

12/11/2015, 3:33:29 PM

Confirmations

5,445,289

Mined by

⛏️ P2SHAY7W35XKC445PShmpoBwg2gE7oyf8SSb5i

Merkle Root

621a84e1f97b1bad15c62d0267dde22f2c2f7bf9e2f8a838196f5c0cabafa904
Transactions (2)
Coinbase6b5acf79401dee…6f3f120dedfd81
1 in β†’ 1 out8.5000 XPM109 B
AY7W35XK…yf8SSb5i
eb5d3c3e6aefd3…00c2c9e3071979
2 in β†’ 2 out3.0836 XPM373 B
AXSDKdy4…xETxJwj7AXjH5J3t…RGMYabBx
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.

1.924 Γ— 10⁹⁴(95-digit number)
19247983804379599032…90326949965059290881
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
1.924 Γ— 10⁹⁴(95-digit number)
19247983804379599032…90326949965059290881
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
2
2^1 Γ— origin + 1
3.849 Γ— 10⁹⁴(95-digit number)
38495967608759198065…80653899930118581761
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
3
2^2 Γ— origin + 1
7.699 Γ— 10⁹⁴(95-digit number)
76991935217518396131…61307799860237163521
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
4
2^3 Γ— origin + 1
1.539 Γ— 10⁹⁡(96-digit number)
15398387043503679226…22615599720474327041
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
5
2^4 Γ— origin + 1
3.079 Γ— 10⁹⁡(96-digit number)
30796774087007358452…45231199440948654081
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
6
2^5 Γ— origin + 1
6.159 Γ— 10⁹⁡(96-digit number)
61593548174014716905…90462398881897308161
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
7
2^6 Γ— origin + 1
1.231 Γ— 10⁹⁢(97-digit number)
12318709634802943381…80924797763794616321
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
8
2^7 Γ— origin + 1
2.463 Γ— 10⁹⁢(97-digit number)
24637419269605886762…61849595527589232641
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
9
2^8 Γ— origin + 1
4.927 Γ— 10⁹⁢(97-digit number)
49274838539211773524…23699191055178465281
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
10
2^9 Γ— origin + 1
9.854 Γ— 10⁹⁢(97-digit number)
98549677078423547048…47398382110356930561
Verify on FactorDB β†—Wolfram Alpha β†—
Γ—2βˆ’1 β†’
11
2^10 Γ— origin + 1
1.970 Γ— 10⁹⁷(98-digit number)
19709935415684709409…94796764220713861121
Verify on FactorDB β†—Wolfram Alpha β†—

What this block proved

The miner who found this block proved the existence of 11 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.

β˜…β˜…β˜…β˜†β˜†
Rarity
RareChain length 11

Approximately 1 in 1,000 blocks. Noteworthy discoveries.

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, …
Cross-reference on Chainz Explorer
Circulating Supply:57,730,321 XPMΒ·at block #6,810,777 Β· updates every 60s
xpmprime.info is a work in progress. If you enjoy using this service you can support this project with a Primecoin donation.
AQZeJoQ81VgeHQBpEYTgvNqV1gnz3L5SvK

Cookie Preferences

We use cookies to enhance your experience. Some are essential for the site to function, while others help us understand how you use the site.

Β·Privacy Policy