Block #2,732,707

2CCLength 11★★★☆☆

Cunningham Chain of the Second Kind · Discovered 7/3/2018, 4:05:53 PM · Difficulty 11.6318 · 4,103,637 confirmations

2CC
Cunningham Chain of the Second Kind

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

Block Header
Block Hash
39b9db29c74728a6bc1f61e343e123526c8c2e91ab0bc42418b0d4a9eabb179d

Height

#2,732,707

Difficulty

11.631807

Transactions

7

Size

2.87 KB

Version

2

Bits

0ba1be22

Nonce

1,174,532,168

Timestamp

7/3/2018, 4:05:53 PM

Confirmations

4,103,637

Merkle Root

9aec35d1f5d1236a5386142d5df3d8b3e0e98675b0be78a9c413d18ae28294c4
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.

5.842 × 10⁹⁴(95-digit number)
58428668632597766225…68088787191703454721
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
5.842 × 10⁹⁴(95-digit number)
58428668632597766225…68088787191703454721
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
2
2^1 × origin + 1
1.168 × 10⁹⁵(96-digit number)
11685733726519553245…36177574383406909441
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
3
2^2 × origin + 1
2.337 × 10⁹⁵(96-digit number)
23371467453039106490…72355148766813818881
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
4
2^3 × origin + 1
4.674 × 10⁹⁵(96-digit number)
46742934906078212980…44710297533627637761
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
5
2^4 × origin + 1
9.348 × 10⁹⁵(96-digit number)
93485869812156425961…89420595067255275521
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
6
2^5 × origin + 1
1.869 × 10⁹⁶(97-digit number)
18697173962431285192…78841190134510551041
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
7
2^6 × origin + 1
3.739 × 10⁹⁶(97-digit number)
37394347924862570384…57682380269021102081
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
8
2^7 × origin + 1
7.478 × 10⁹⁶(97-digit number)
74788695849725140769…15364760538042204161
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
9
2^8 × origin + 1
1.495 × 10⁹⁷(98-digit number)
14957739169945028153…30729521076084408321
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
10
2^9 × origin + 1
2.991 × 10⁹⁷(98-digit number)
29915478339890056307…61459042152168816641
Verify on FactorDB ↗Wolfram Alpha ↗
×2−1 →
11
2^10 × origin + 1
5.983 × 10⁹⁷(98-digit number)
59830956679780112615…22918084304337633281
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:57,935,010 XPM·at block #6,836,343 · updates every 60s
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