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arithmetic series
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The indicated sum of all terms in an arithmetic sequence. One such example is:
1 + 2 + 3 + . . . + 100 The general formula for an arithmetic series is: Sn | = a1 + a2 + a3 + . . . + an | | = a1 + (a1 + d) + (a1 + 2d) + . . . + [a1+(n-1)d] | | = n(a1 + an)/2 | | = n[2a1 +(n-1)d]/2 |
In the example, the first term, a1, is 1, and the last term, a100, is 100. Using the formula, the sum = 100(1+100)/2 = 5050.
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