Find the general formula of sequence: 2, - 6,18, - 54,112 | Math enthusiast | Mathematical art

Find the general formula of sequence: 2, - 6,18, - 54,112

Should 112 be 162?
If so, there are:
an=(-1)^(n+1)*2*3^(n-1)

A general formula sequence 2, - 6,81, - 54... A general formula process

If 81 should be 18, then: (- 6) = 2 × (- 3) 18 = (- 6) × (- 3) - 54 = 18 × (- 3) rule: starting from the second item, each item is equal to its preceding item multiplied by - 3, in fact, the sequence is headed by 2

Sequence 1, 3, 7, 15 The general formula of an is equal to______ ．

a2-a1=21，a3-a2=22，a4-a3=23，… By analogy, we can get an-an-1 = 2N-1  a2-a1 + a3-a2 + a4-a3 +an-an-1=an-a1=21+22+23+… +2N-1 = 2n-2  an-a1 = 2n-2, an = 2N-1, so the answer is 2N-1

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