Question

which series is it 2+6+12 and so on to n​and what is the difference between them
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Answer 1

Find the nth term of the sequence: 2, 6, 12, 20, 30... Clearly the required sequence is double the one we have found the nth term for, therefore the nth term of the required sequence is 2n(n+1)/2 = n(n + 1). The Fibonacci sequence is an important sequence which is as follows: 1, 1, 2, 3, 5, 8, 13, 21, ... .