Question

I need to find the nth term for this number sequence: 1,1 2,6 3,15 4,28 5,45 6,66. I need to fine the 20th term.

Answer 1

\begin{array}l\color{red}{\normalsize\text{ǝ}}\color{orange}{\normalsize\text{u}}\color{#9c9a2e}{\normalsize\text{o}}\color{green}{\normalsize\text{ʎ}}\color{blue}{\normalsize\text{ɹ}}\color{purple}{\normalsize\text{ǝ}}\color{purple}{\normalsize\text{ʌ}}\color{red}{\normalsize\text{Ǝ}}\color{orange}{\normalsize\text{ }}\color{#9c9a2e}{\normalsize\text{o}}\color{green}{\normalsize\text{l}}\color{blue}{\normalsize\text{l}}\color{purple}{\normalsize\text{ǝ}}\color{purple}{\normalsize\text{H}}\color{red}{\normalsize\text{}}\end{array}

Answer 2

n:1 2 3 4 5 6
A:1 6 15 28 45 66
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hmm, gotta look for patterns

Answer 3

there is no set way to get a good feel for these ... not that ive found

Answer 4

1*1
2*3
3*5
4*7
5*9

Answer 5

n(2n-1) seems right

Answer 6

that 1,3,5,7,9 pattern is a good thing to put to memory; (2n-1)

Answer 7

now that we have a formula; lets use n=20 and solve

Answer 8

does that make sense?

Answer 9

yes it does thank you

Answer 10

good :)