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August 30, 2015
Posted by **Luis** on Tuesday, January 5, 2010 at 11:23pm.

2+8+18+32+50+72

- Calculus -
**MathMate**, Wednesday, January 6, 2010 at 12:11amCalculate the difference between successive terms of the sum. The differences are the terms you need to add together to make the sum.

Sum: 2,8,18,32,50,72...

diff: 2,6,10,14,18,22...

0th term=2

1st term = 6

2nd term = 10

The rule is therefore 2+4i

So check if Σ2+4i works for you. i starts from zero.

- Correction -
**MathMate**, Wednesday, January 6, 2010 at 12:19amMy answer above applies if the list of numbers were successive sums.

Go with Reiny's answer:

http://www.jiskha.com/display.cgi?id=1262752887