2. - 4.6. - 8.10. - 12, 14, - 16 the 99th number is the 100th number | Math enthusiast | Mathematical art

2. - 4.6. - 8.10. - 12, 14, - 16 the 99th number is the 100th number

an=(-1)^(n-1)*2n
The 99th number is: 2 * 99 = 198
The 100th number is: - 1 * 2 * 100 = - 200

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