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Term # | Blocks | Total
| added | Blocks
------------------------------
1. | 25 | 25
2. | 18 | 43 = 25+1(18)
3. | 18 | 51 = 25+2(18)
4. | 18 | 69 = 25+3(18)
5. | 18 | 87 = 25+4(18)
... | ... | ...
Nth. | 18 | 25+(n-1)18
Then simplify 25+(n-1)18
25+18n-18
7+18n
Edwin