Simpler congruences for Jacobi sum $J(1,1{)}_{49}$ of order 49

In this paper we determine the congruence of Jacobi sums $J(1,1{)}_{49}$ of order 49 over a field ${\mathbb{F}}_p$. We also show that simpler congruences hold for $J(1,1{)}_{49}$ in the case of artiad and hyperartiad primes.