this: the numbers of interest are should be written as follow:

the numbers of interest are (the numbers from whole range from 0 to n, containg 1 as a digit)

it would be more clear.

Please let me know the explanation to this part:

nb_dig(25, 1):
the numbers of interest are
1, 4, 9, 10, 11, 12, 13, 14, 19, 21 which squared are 1, 16, 81, 100, 121, 144, 169, 196, 361, 441
so there are 11 digits 1 for the squares of numbers between 0 and 25.

if k is between 0 and n, I assume it should be:

rawK = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25}

instead of:

rawK = {1, 4, 9, 10, 11, 12, 13, 14, 19, 21 }

?

in select satatement what exactly do then part? is there any possibility to use given labels?

Finished with 'panjabi' code style.
IMHO it should be ZULU format first (23:15 -> twenty-three fifteen, 14:00 -> fourteen hundrets)

Personally I do not understand why to use postgreSQL, in comparision to MariaDB it is like going for shopping with tank.

For mysql coders it gives a hard time. Somehow it should be possible to determine the other variants are possible or not (like mysql language implementation)

I love the oneline shots in python but it gives me hard time, everytime I try to make the solution that way I get the failure and finish with if a == b: Bleeh

To OP, add one test line with "I am.." on the beginning to prevent age[0] workaround.

As I see my solution is quite similar to others, which means it is not a solution to the real problem.
The real problem I understand is: we got pipes, and we need to check which pipe is missing, and put them into the correct place.
What we have done is: we removed all the pipes (we do not care for material!) and we make a perfect new installation.
I wonder who would pay for that fix.

The proper solution should be as follow

pipes = ['1', '2', '4']
we see there is lack of pipe number '3'
we take a pipe
we put the pipe into the proper slot
pipes = ['1', '2', '3', '4']
all old pipes are the same, but we added only one pipe!

The Op should give a direct order: either to recode nor to find the mistakes. The solution based on new code instead of finding the gap is not a solution IMHO.

I got an error when full test was done. But I could not see any input. I am ashame because I made a patch in code, but would be glad to know what is the full input.