Block #898,077

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 1/17/2015, 1:15:56 AM · Difficulty 10.9445 · 5,916,393 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
d7fc72808bab62a5717eeacdac9edd7d98ea6f1d91e5792ac4b2b84e602a5148

Height

#898,077

Difficulty

10.944545

Transactions

11

Size

5.00 KB

Version

2

Bits

0af1cdac

Nonce

1,726,138,112

Timestamp

1/17/2015, 1:15:56 AM

Confirmations

5,916,393

Merkle Root

0687d07a0d0d4f7f0e752dbbe1e763bc7cc7fcc33a408755d5274d116ae74e73
Prime Chain Origin

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

1.903 × 10⁹⁴(95-digit number)
19036855885336608691…94907534084791906321
Discovered Prime Numbers
p_k = 2^k × 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
1.903 × 10⁹⁴(95-digit number)
19036855885336608691…94907534084791906321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
3.807 × 10⁹⁴(95-digit number)
38073711770673217383…89815068169583812641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
7.614 × 10⁹⁴(95-digit number)
76147423541346434767…79630136339167625281
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
1.522 × 10⁹⁵(96-digit number)
15229484708269286953…59260272678335250561
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
3.045 × 10⁹⁵(96-digit number)
30458969416538573906…18520545356670501121
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
6.091 × 10⁹⁵(96-digit number)
60917938833077147813…37041090713341002241
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
1.218 × 10⁹⁶(97-digit number)
12183587766615429562…74082181426682004481
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
2.436 × 10⁹⁶(97-digit number)
24367175533230859125…48164362853364008961
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
4.873 × 10⁹⁶(97-digit number)
48734351066461718251…96328725706728017921
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
9.746 × 10⁹⁶(97-digit number)
97468702132923436502…92657451413456035841
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
1.949 × 10⁹⁷(98-digit number)
19493740426584687300…85314902826912071681
Verify on FactorDB ↗Wolfram Alpha ↗

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 — the large number shown above — anchors the chain and is divisible by a primorial (the product of small primes), cryptographically tying these prime numbers to this specific block.

★★★☆☆
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 × 3 × 5 × 7 × …), the result is the first prime in the chain. The origin is deliberately divisible by this primorial — that divisibility is part of the proof.

Prime Chain Origin = First Prime × Primorial (2·3·5·7·11·…)
Source: Primecoin prime.cpp — CheckPrimeProofOfWork()

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

2CC: p₁ (first prime), p₂ = 2p₁ − 1, p₃ = 2p₂ − 1, …
Circulating Supply:57,759,834 XPM·at block #6,814,469 · updates every 60s
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