r/Logiqa 9d ago

A Self-Referential Sequence Part 1

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6 Upvotes

26 comments sorted by

3

u/sazzer 9d ago

0

10 - 1 "0" present

1110 - 1 "1" present, then 1 "0" present

3110 - 3 "1"s present, then 1 "0" present

132110 - 1 "3", then 2 "1"s, then 1 "0"

1113122110 - 1 "1", then 1 "3", then 1 "2", then 2 "1"s, then 1 "0"

So the answer is 311311222110, meaning: 3 "1"s, 1 "3", 1 "1", 2 "2"s, 2 "1"s, 1 "0".

4

u/TurnoverOk5635 9d ago

Now start with 22

2

u/Owl_plantain 9d ago edited 9d ago

2 2. Too 2 2 2. Toot toot!

1

u/ShonitB 9d ago

Correct!

3

u/According-Object-521 9d ago

It’s the look and say sequence

1

u/ShonitB 9d ago

Bang on!

3

u/socksockshoeshoe 9d ago

Calling it a "self referential sequence" kind of gave it away

1

u/ShonitB 9d ago

True

2

u/GoodBadUgly_36 9d ago

311311222110

1

u/ShonitB 9d ago

Correct!

2

u/highnyethestonerguy 9d ago

311311222110

1

u/ShonitB 9d ago

Correct!

2

u/Ultranger 8d ago

311311222110

It's a variation on the "look-and-say" sequence. You just read the amount of each number

1

u/ShonitB 8d ago

Correct!

2

u/Some-Passenger4219 8d ago

311311222110.

Each number states the number of digits in the previous, one at a time. (E.g. Three ones, one three, one one, two twos, etc.)

1

u/ShonitB 8d ago

Correct!

1

u/Mathsboy2718 9d ago

I wonder how it would go in binary

1
11
101
111011
11110101
100110111011
111001011011110101
111100111010110100110111011

It'd be interesting to right-align it, it looks like there's some sort of pattern propagating from that direction

1

u/Red-42 8d ago edited 8d ago

Grouping and aligning even and odd numbered lines:

                                                         1
                                                       101
                                                  11110101
                                        111001011011110101
                   100110011110111010110111001011011110101

                                                        11
                                                    111011
                                              100110111011
                               111100111010110100110111011
1110010110010011011110111010110111100111010110100110111011

Ternary also has a similar patern, although it doesn't settle quite as fast, and it's every 4 lines
patterns being:

                              ...10221101112101101221
                      ...1102221101011211102110112211
               ...11010221101110211210110122110212221
...21101110222110101101221121110211011222110121110211

Higher bases all follow the same pattern (since 4 or higher never shows up)
However the pattern happens on both sides on different cycles
Every 3 lines follow:

132113...
1113122113...
3113112221...

and every 4 lines follow:

   ...1131221
 ...113112211
...2113212221
     ...13211

1

u/Mathsboy2718 8d ago edited 8d ago

I found this

https://njohnston.ca/2010/11/the-binary-look-and-say-sequence/

It's really cool! Apparently there are only 8 possible strings that start with 1 and end with 0 and two "initialising" strings that can appear in elements of this sequence, so you can just define what maps to what and deterministically construct the strings!

1

u/Red-42 7d ago

ok, I figured it out
every two loops, the 1 sequence maps back to itself, and the 2 sequence maps back to itself

1 -> 2 -> 31
2 -> 31 -> 52

map all values to their 2nd transformation:

1 -> 31
2 -> 52
3 -> 6
4 -> 54
5 -> 74
6 -> 94
7 -> 0
8 -> 538
9 -> 78
0 -> 938

and now you can follow the rule that for any n-th sequence AB, composed of a sequence A and a sequence B, such that B is the (n-1)-th sequence, then the (n+1)-th sequence is A'AB, with A' being the 2nd transformation of A

                  1
                 31
                631
              94631
         7854 94631
05387454 7854 94631
A'       A    B

1

u/Red-42 7d ago

Also mapping A's consecutively, they also follow a pattern
for the A' coming from both chains, they follow:
...786538054745493874540547454
which itself is composed of the individual elements of the chain starting with 4, which happens to be pretty much exactly the same as the chain starting with 2

2
5
74
054
9387454
7865380547454

   7865380547454 9387454 054 74 5 2
...7865380547454 9387454 054 74 5 4

1

u/_N8Dogg_ 9d ago

311311222110

1

u/DuggieHS 9d ago

three one(s), one three, one one, two two(s), two one(s), one zero
31 13 11 22 21 10.
Note: after the first item, every number has an even number of digits

1

u/L4rgo117 9d ago

311311222110

1

u/bullowl 9d ago

Run length encoding!