In this paper, we mainly prove the following conjectures of Z.-W. Sun (J. Number Theory 133 (2013), 2914–2928): let p>2
be a prime. If p=x^2+3y^2
with x,y\in \mathbb {Z}
and x\equiv 1\ ({\rm {mod}}\ 3)
, then
x\equiv\frac14\sum_{k=0}^{p-1}(3k+4)\frac{f_k}{2^k}\equiv\frac12\sum_{k=0}^{p-1}(3k+2)\frac{f_k}{({-}4)^k}\ ({\rm{mod}}\ p^2), 
and if
p\equiv 1\pmod 3
, then
\sum_{k=0}^{p-1}\frac{f_k}{2^k}\equiv\sum_{k=0}^{p-1}\frac{f_k}{({-}4)^k}\ ({\rm{mod}}\ p^3), 
where
f_n=\sum _{k=0}^n\binom {n}k^3
stands for the
n
th Franel number.