Any triangle can be broken into 4 smaller and equal triangles, with a remainder, depending on u parity.
T(u) = 4*T(u') + rm
odd u
u' = (u-1)/2
rm = u - (u-1)/2
even u
u' = (u-2)/2
rm = u + u/2
Pic attached for u10025 - 10050 shows these results.
Any triangle can be broken into 4 smaller and equal triangles, with a remainder, depending on u parity.
T(u) = 4*T(u') + rm
odd u
u' = (u-1)/2
rm = u - (u-1)/2
even u
u' = (u-2)/2
rm = u + u/2
Pic attached for u10025 - 10050 shows these results.
reviewing polite numbers again.
> Sum of polite numbers is the same as their difference of squares.
The count of numbers in a polite range is either one of the factors of c or twice that factor.
The sum of the first and last numbers in a polite range is also either one of the factors of c or twice that factor.
Examples attached for c34117=109x313, c260891=317x823, and c208255331=5449x38219.
The "(first+last)/2" column only divides even numbers by 2.
Posting some previous work which explored finding non-trivial records in the grid for multiplication.
Pic attached shows the results for c*d multiples of records between c300 and c400.
The trivial record is in the "c=cd" column.
The non-trivial record is in the "a,b" column.
Non-trivial records are created using the "formula" column. The rules can be summarized as follows:
odd c * odd d =a=d, b=c
odd c * even d, d%4=0 =a=d/2, b=2c
odd c * even d, d%4=2 =a=d/2, b=c
even c * even d =a=d, b=c
even c * odd d =a=2d, b=c/2
The d%4=2 exception is because the resulting c will also be mod 4 = 2, and must be divided by 2 to create a valid record.
Given e and t in row 1, we can calculate d, f, and j.
even e, d = 4T(t-1) + e/2
odd e, d = 2(t^2) + (e-1)/2
f = 2d+1-e.
j = sqrt(f)
Subsequent e columns can be found by looping until j=1:
j = j - 1;
d = d - 1;
f = j * j;
e = 2 * d + 1 - f;
First pic attached shows the list of records starting from (1,1,5) where a=41. The last 2 records correspond to (2a-1,1,1) and (2a,1,1).
Also attached are examples of e columns with matching a values in (1,1) and (2,1) for t=1 to 10.