• Salih Dincer (11/23) Jun 24 Hello, I discovered something about octal prime numbers. I don't
• Salih Dincer (32/35) Jun 27 Since we couldn't get a code snippet, I'd like to share some

Salih Dincer <salihdb hotmail.com> writes:

Hello, I discovered something about octal prime numbers. I don't 
know if anyone has dealt with this before, but thanks to the 
power of the D programming language, it was very easy. So, by 
defining a range with the empty(), front() and popFront() 
functions, I produced an output, something like this:

 ~ dmd main.d -ofmain.out
 ~ ./main.out
 00000000000000000005: 5, 0
 00000000000000000045: 37, 1
 00000000000000000445: 293, 2
 00000000000000004445: 2341, 3
 00000000000044444445: 9586981, 7
 00000000004444444445: 613566757, 9
 00000000044444444445: 4908534053, 10
 44444444444444444445: 658812288346769701, 19
 ...
 4...4444444444444445: ? (hint: greater than 100 bits)

In order, they are as follows "octal: decimal, and number of 
repetitions (¹⁰¹) and they are all prime 8 numbers! So what's the 
ninth? I'm not sharing the code for now because it's a challenge. 
But you should use std.bigint module and simply shift left and 
add octal 4 or binary 101.

SDB 79

Salih Dincer <salihdb hotmail.com> writes:

On Tuesday, 25 June 2024 at 06:44:28 UTC, Salih Dincer wrote:
 
 I'm not sharing the code for now because
 it's a challenge.

Since we couldn't get a code snippet, I'd like to share some 
framing code without answers:

```d
struct SumPrimes(size_t size)
{
   import std.bigint;

   auto next = BigInt(1);
   auto power = BigInt(4);
   size_t index;

   auto empty() => index > size;
   auto front() => next + power;
   auto popFront()
   {
     // ...
     index++;
   }
}

unittest
{
   for (auto p = SumPrimes!10(); !p.empty; p.popFront())
   {
     auto n = p.front();
     if (n.isPrime)
     {
       n.writef!"%11o: ";
       n.writeln(", ", p.index);
     }
   }
}
```

SDB 79