a(3)=32套系统:
{12}{13}{23} {1}{12}{13}{23} {1}{2}{12}{13}{23} {1}{2}{3}{12}{13}{23}
{12}{13}{123} {2}{12}{13}{23} {1}{3}{12}{13}{23} {1}{2}{3}{12}{13}{123}
{12}{23}{123} {3}{12}{13}{23} {2}{3}{12}{13}{23} {1}{2}{3}{12}{23}{123}
{13}{23}{123} {1}{12}{13}{123} {1}{2}{12}{13}{123} {1}{2}{3}{13}{23}{123}
{1}{12}{23}{123} {1}{2}{12}{23}{123}
{1}{13}{23}{123} {1}{2}{13}{23}{123}
{2}{12}{13}{123} {1}{3}{12}{13}{123}
{2}{12}{23}{123} {1}{3}{12}{23}{123}
{2}{13}{23}{123} {1}{3}{13}{23}{123}
{3}{12}{13}{123} {2}{3}{12}{13}{123}
{3}{12}{23}{123} {2}{3}{12}{23}{123}
{3}{13}{23}{123} {2}{3}{13}{23}{123}
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