zeta({{2}^m, 1, {2}^m, 3}^n, {2}^m) / π^(4n + 2m(2n+1)) is rational

The cyclic insertion conjecture of Borwein, Bradley, Broadhurst and Lison\v{e}k states that inserting all cyclic shifts of some fixed blocks of 2's into the multiple zeta value {\zeta}(1,3,...,1,3) gives an explicit rational multiple of a power of {\pi}. In this paper we use motivic multiple zeta values to establish a non-explicit symmetric insertion result: inserting all possible permutations of some fixed blocks of 2's into {\zeta}(1,3,...,1,3) gives some rational multiple of a power of {\pi}.