8
3 5
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Place unique positive integers into a pyramid such that each number equals the sum of the two numbers below it. Minimize the top number. A solution for three rows is above. Solve for 4, 5, and 6 rows. (or more...). To remove reflections in submissions, let the lower left corner be less than the lower right.
Source: Original. Based on what ought to be a classic puzzle I found in the recent Games Magazine, with 6 rows and the top number of 100.