$1+(1+3)+(1+3+5)+(1+3+5+7)+\ldots$ to $10$ terms $=$

If the sum of the first $n$ terms of a series is $5n^2 + 2n$,then its second term is

If $S_{n} = 4 + 11 + 21 + 34 + 50 + \ldots$ to $n$ terms,then $\frac{1}{60}(S_{29} - S_{9})$ is equal to $.......$.

The number of solutions of $2^{1+|\cos x|+|\cos x|^2+\ldots} = 4$ in $(-\pi, \pi)$ is

What is the sum of the first $10$ terms of the series $0.7 + 0.77 + 0.777 + \dots$?

If the sum of the series $1^2 + 2 \cdot 2^2 + 3^2 + 2 \cdot 4^2 + 5^2 + \dots + 2 \cdot (n-1)^2 + n^2$ (when $n$ is odd) is to be determined,given that for even $n$,the sum is $\frac{n(n+1)^2}{2}$,find the sum when $n$ is odd.