a 01 01
b 02 02
c 03 03
d 04 04
e 05 05
f 06 06
g 07 07
h 08 08
i 09 09

j 10 01
k 11 02
l 12 03
m 13 04
n 14 05
o 15 06
p 16 07
q 17 08
r 18 09

s 19 01
t 20 02
u 21 03
v 22 04
w 23 05
x 24 06
y 25 07
z 26 08

1 a j s
2 b k t (11 -> 2)
3 c l u
4 d m v (22 -> 4)
5 e n w
6 f o x (33 -> 6)
7 g p y
8 h q z
9 i r

<https://en.wikipedia.org/wiki/Luoshu_Square>

Here is a simple algorithm in Rust that converts a letter from the first set to the second set:

```rust
fn convert_letter(c: char) -> char {
    let offset = (c as u8 - 'a' as u8) * 2 + 1;
    (offset as char).to_uppercase().next().unwrap()
}
```

And here is the algorithm to convert a letter from the second set back to the first set:

```rust
fn convert_letter_back(c: char) -> char {
    let offset = (c as u8 - 'A' as u8) / 2;
    (offset as char + 'a' as u8) as char
}


assert_eq!(convert_to_number("abc"), 123);
assert_eq!(convert_to_number("jst"), 578);
assert_eq!(convert_to_letter(123), "abc");
assert_eq!(convert_to_letter(578), "jst");



fn convert_to_number(s: &str) -> u32 {
    let mut result = 0;
    for c in s.chars() {
        let offset = (c as u32) - ('a' as u32);
        result = result * 10 + (offset / 3) + 1;
    }
    result
}

fn convert_to_letter(n: u32) -> String {
    let mut result = String::new();
    let mut n = n;
    while n > 0 {
        let digit = (n % 10) as u8 - 1;
        n /= 10;
        result.push(((digit * 3) + 'a' as u8) as char);
    }
    result.chars().rev().collect()
}

```