(PARI)
permcount(v)={my(m=1,s=0,k=0,t);对于(i=1,#v,t=v[i];k=if(i>1&&t==v[i-1],k+1,1);m*=t*k;s+=t);s!/m}
边(v)={和(i=2,#v,和(j=1,i-1,gcd(v[i],v[j]))+和(i=1,#v,v[i]\2)}
dom(u,v)={prod(i=1,#u,2^sum(j=1,#v,gcd(u[i],v[j]))-1)}
U(nb,nw)={my(s=0);对于零件(U=nw,my(t=0));对于部件(v=nb,t+=permcount(v)*2^边(v)*dom(U,v));s+=t*permcounts(U)*2`边(U)/nb!);s/nw!}
a(n)={和(k=0,n,U(k,n-k))}