what is the rule of this sequence?

What is the rule of this sequence?
$10,~15,~25,~40,~60,~\dots$

how do u get the rule and what type of sequence is this

$\begin{array}{|rcll|} \hline n & a_n & d_0 & d_1 \\ \hline 1 & 10 & \\ & & +5 \\ 2 & 15 & & +5 \\ & & +10 \\ 3 & 25 & & +5\\ & & +15 \\ 4 & 40 & & +5\\ & & +20\\ 5 & 60 & \\ \hline \end{array}$

This is an Arithmetic Sequences Second order
$\mathbf{an^2 + bn + c = a_n}$ with a, b, and c integers

$\begin{array}{|lrcll|} \hline n=1: & a*1^2 + b*1 + c &=& 10 \\ n=2: & a*2^2 + b*2 + c &=& 15 \\ n=3: & a*3^2 + b*3 + c &=& 40 \\ \hline (1) & a+b+c &=& 10 \\ (2) & 4a+2b+c &=& 15\\ (3) & 9a +3b + c &=& 25 \\ \Rightarrow & a&=& \dfrac{5}{2} \\ \Rightarrow & b&=& -\dfrac{5}{2} \\ \Rightarrow & c&=& 10 \\ \hline & a_n &=& \dfrac{5}{2}*n^2 -\dfrac{5}{2}*n + 10 \\ \hline \end{array}$

Question:    Can you just write this as a recursive sequence

    a₁ =10   ,   a_n = a_n-1   + 5 ( n-1)            ?????

Thanx !    ~ EP