Question 1105091
Look at the initial value 3.
To that, when n=0, 3+n=3 for the first value.
Every value after that goes up 7
So (3+7(0))+(3+7(1))+(3+7(2)) is the pattern.
So it is the sum of n=0 to 17 (that is 18 unique rows) of 3+7n.
Need to know a18, the 18th and final sum.  That is 3+7(17)=122, the first row +the increase each row* the number of rows minus 1
Sum=(n/2)(a1+an)=(18/2)(3+122)=9*(125)=1125
3,10,17,24,31,38,45,52,59,66,73,80,87,94,101,108,115,122=1125