a(2)=2和a(3)=6多系统:
{1,1} {{1},{1,1}}
{1,2} {{1},{1,2}}
{{1},{2,3}}
{{2},{1,1}}
{{2},{1,3}}
{{3},{1,2}}
a(4)=43个多系统(省略逗号和外括号):
{{1}}{{1}{11}} {{1}}{{1}{12}} {{1}}{{1}{22}} {{1}}{{1}{23}} {{1}}{{2}{34}}
{{11}}{{1}{1}} {{11}}{{1}{2}} {{11}}{{2}{2}} {{11}}{{2}{3}} {{12}}{{3}{4}}
{{1}}{{2}{11}} {{1}}{{2}{12}} {{1}}{{2}{13}} {{1}}{{3}{24}}
{{12}}{{1}{1}} {{12}}{{1}{2}} {{12}}{{1}{3}} {{13}}{{2}{4}}
{{2}}{{1}{11}} {{2}}{{1}{12}} {{1}}{{3}{12}} {{1}}{{4}{23}}
{{2}}{{2}{11}} {{13}}{{1}{2}} {{14}}{{2}{3}}
{{22}}{{1}{1}} {{2}}{{1}{13}} {{2}}{{1}{34}}
{{2}}{{3}{11}} {{2}}{{3}{14}}
{{23}}{{1}{1}} {{23}}{{1}{4}}
{{3}}{{1}{12}} {{2}}{{4}{13}}
{{3}}{{2}{11}} {{24}}{{1}{3}}
{{3}}{{1}{24}}
{{3}}{{2}{14}}
{{3}}{{4}{12}}
{{34}}{{1}{2}}
{{4}}{{1}{23}}
{{4}}{{2}{13}}
{{4}}{{3}{12}}