Table of n, a(n) for n=3..8.
Frank Thomson Leighton, Margaret Lepley, and Gary L. Miller, Layouts for the shuffle-exchange graph based on the complex plane diagram, SIAM J. Algebraic Discrete Methods 5 (1984), no. 2, 202--215. MR0745439 (85j:68056). See Table 1.
Eric Weisstein's World of Mathematics, Shuffle-Exchange Graph