Question

1+(1+4)+(1+4+7)+(1+4+7+10)....................................................+∞
What is the general term and summation of the series?

Answer 1

actually better to add these in parentheses

Answer 2

= 1 + 5 + 12 + ..

Answer 3

so you want to sum the series
1 + 5 + 12 + 22 + ...
well the sum is obvious infinity

Answer 4

this is a quadratic sequence
1,5,12,22, ...

Answer 5

the terms in each parentheses forms an A. P, with the first term 1 and common difference 3.

Answer 6

akitav, not quite, they keep increasing

Answer 7

its a quadratic progression, not arithmetic

Answer 8

I want to know the sum of 'n' terms of the series. And bye the way what is the general term?

Answer 9

the general term is a pentagonal sequence

Answer 10

http://en.wikipedia.org/wiki/Pentagonal_number