It is convenient to let a spreadsheet program fill these in. If you don't know how to use one, learn. Very good ones are available for free on the web.
See the attachment for the table values.
Obviously, the patterns are similar in that each row is multiplied by some constant to get the next row. They are different in that the constants are different. 2 is used for the left column, so the reward grows less fast than in the right column where 3 is used.
The King's Plan 2 will only be cheaper if the number of squares being filled is less than about 5/8 of the number of squares in the original Plan 1.