Ken's Puzzle of the Week

Sum Pyramid

  3   5  
2   1   4

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.

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