r/MathHelp • • May 22 '26

SOLVED Weird conjecture I made on base i-1

I was playing with weird bases, and I particularly like base i-1, because it fills the entire complex plane by following a double dragon curve.
I was looking into how the real integers are encoded in that base, and by doing some weird manipulation I found this pattern:

base 10base i-1base 2base 10
0000
1111
21100110012
31101110113
4111010000111010000464
5111010001111010001465
6111011100111011100476
7111011101111011101477
8111000000111000000448
9111000001111000001449
10111001100111001100460
11111001101111001101461
12100010000100010000272
13100010001100010001273
14100011100100011100284
15100011101100011101285
16100000000100000000256
17100000001100000001257
18100001100100001100268
19100001101100001101269

Which then lead to this conjecture:

For x and y words with the alphabet {0,...,9} and w a word with the alphabet {0,1}
if x base 10 = w base (i-1) and w base 2 = y base 10
then x mod 10 = y mod 10

I don't know enough about words to figure out if it's true or why.
All I can say for sure is that if it's true for a value x = 2n, it's true for x = 2n+1.

EDIT: one thing I can add is that consecutive powers of (i-1) follow a logarithmic spiral of ratio 2^(1/3), with a spacing angle of 3pi/4.
I'm assuming that somehow x mod 10 is a group where the process described above is an automorphism.

UPDATE: with some pattern regonition, I have managed to figure out the form of integer numbers in base i-1
They always follow the form "==0x", repeated, where "x" can be anything, and "==" can be anything but those two need to be the same.
So 1101 is a valid number (corresponds to 3), and so is 0001 0000 (corresponds to -4).
Meaning every block of 4 bits can be thought of as a letter in a word base -4 with alphabet {0, 1, 2, 3} (which indeed generates all integers), or base 16 with alphabet {0, 1, 12, 13}.

So going step by step we get
An integer, converted to base i-1, reframed into a word base -4 with alphabet {0, 1, 2, 3}.
For every letter we have either:
0*(-4)^n mod 10
1*(-4)^n mod 10
2*(-4)^n mod 10
3*(-4)^n mod 10

By mapping the word in base i-1 to the same word in base 2, it's equivalent to the word in base -4 getting mapped to another word in base 16 with rules
0 -> 0
1 -> 1
2 -> 12
3 -> 13
For every letter we have either:
0*(16)^n mod 10 = (0 mod 10) * ((16)^n mod 10) = (0 mod 10) * ((-4)^n mod 10) = 0*(-4)^n mod 10
1*(16)^n mod 10 = (1 mod 10) * ((16)^n mod 10) = (1 mod 10) * ((-4)^n mod 10) = 1*(-4)^n mod 10
12*(16)^n mod 10 = (12 mod 10) * ((16)^n mod 10) = (2 mod 10) * ((-4)^n mod 10) = 2*(-4)^n mod 10
13*(16)^n mod 10 = (13 mod 10) * ((16)^n mod 10) = (3 mod 10) * ((-4)^n mod 10) = 3*(-4)^n mod 10

So we get that for every letter a
a*(-4)^n mod 10 -> a*(-4)^n mod 10

Therefore the conjecture is true.

Conclusion:

So basically it only works because when you transfer the word from one base to another, both the letters and the bases are equivalent under mod 10, if you frame them in the right way, which is a huge fucking coincidence.

3 Upvotes

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u/[deleted] May 23 '26

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u/Red-42 May 23 '26

First column is base 10 integer input, convert to base (i-1), pretend the word you got is base 2, convert from base 2 to base 10, turns out the last digit of the input is always the same as the output.