For a Binomial$(n,p)$ random variable $X$, I'm interested in showing that 
$$
\frac{P(X>c)}{P(X>c-1)}=1-o(1)
$$
uniformly in $c\in\mathcal{R}$, where $\mathcal{R}$ is the range of interest (Note that $c$ will vary with $n$). The $o(1)$ rate is meant as $n\to\infty$.

Now I have the following results (Note that $q=1-p$):

> **Result 1**
For $0\leq k\leq n$, set 
$$
P(X=k)=\frac{1}{\sqrt{2\pi pq n}}\exp\left(-\frac{(k-np)^2}{2npq} \right)(1+\delta_n(k))
$$
Then for every positive real sequence $\{c_n\}$ approaching zero,
$$
\lim_{n\to\infty}\max_{k:|k-np|<c_n n^{2/3}}|\delta_n(k)|=0
$$

-

> **Result 2**
Suppose that $\{a_n\}$ is a sequence of real numbers such that $\lim_{n\to\infty}a_n=+\infty$ and $\lim_{n\to\infty}a_n n^{-1/6}=0$. Then
$$
P(X\geq np+a_n\sqrt{npq})\sim \frac{1}{a_n\sqrt{2\pi}}\exp(-a_n^2/2)
$$
where "$\sim$" means asymptotic equivalence. 

-----------
Now,
\begin{align}
\frac{P(X>c)}{P(X>c-1)}&=\frac{P(X>c-1)-P(X=c)}{P(X>c-1)}\\
&=1-\frac{P(X=c)}{P(X\geq c)}
\end{align}

When $c=np$, we have $P(X=c)\leq Cn^{-1/2}$ and $P(X\geq c)=1/2+o(1)$, so that the ratio is $o(1)$. Denote $\phi(x)=(2\pi npq)^{-1/2}\exp(-x^2/2)$. When $c=np+a_n\sqrt{npq}$, $P(X=c)=n^{-1/2}\phi(a_n)$ and $P(X\geq c)\sim \phi(a_n)/a_n$ so that the ratio is also $o(1)$ because $a_n=o(n^{1/6})=o(n^{-1/2})$.

Can someone help verify if this line of reasoning is correct?