texmath-0.9.4: tests/writers/06.eqn
sum from {m = 1} to inf sum from {n = 1} to inf {m sup 2 ^ n} over {3 sup m left ( m ^ 3 sup n + n ^ 3 sup m right )}
sum from {m = 1} to inf sum from {n = 1} to inf {m sup 2 ^ n} over {3 sup m left ( m ^ 3 sup n + n ^ 3 sup m right )}