  Let $F(X)= \prod_{i=1}^k(a_iX+b_i)$ be a polynomial with $a_i, b_i$ being
integers. Suppose the discriminant of $F$ is non-zero and $F$ is admissible.
Given any natural number $N$, let $S(F,N)$ denotes those integers less than or
equal to $N$ such that $F(n)$ has no prime factors less than or equal to
$N^{1/(4k+1)}.$ Let $L$ be a translation invariant linear equation in $3$
variables. Then any $A\subset S(F, N)$ with $\delta_F(N): =
\frac{|A|}{|S(F,N)|} \gg_{\epsilon, F, L}\frac{1}{(\log \log N)^{1-\epsilon}}$
contains a non-trivial solution of $L$ provided $N$ is sufficiently large.
