1 2 5 5 11 12 12 25 26 27 in c++ soltion with explanation

Question

here 1 is in 1st row
2 & 5 in 2 row
5, 11 & 12 in 3rd row
12, 25, 26& 27 in 4th row

Answer 1

The difference between the first and second number is found woth the sequence 2n^2 - 3n + 4

Answer 2

1) The last number in each rows is the first in the next row.
2) After some increament (not sure what) it has n-1 (where n is the rows) more numbers increamenting by 1.

Answer 3

anyone else?