permcount[v_]:=模[{m=1,s=0,k=0,t},对于[i=1,i<=长度[v],i++,t=v[i]];k=如果[i>1&&t==v[[i-1]],k+1,1];m*=t*k;s+=t];s/m] ;
边[v_]:=2*总和[Sum[GCD[v[i]],v[[j]],{j,1,i-1}],{i,2,长度[v]}]+总和[v];
oddp[v_]:=模块[{i},对于[i=1,i<=长度[v],i++,如果[BitAnd[v[i]],1]==0,返回[0]]];1];
a[n_]:=模[{s=0},Do[If[oddp[p]==1,s+=permcount[2*p]*2^edges[p]*If[OddQ[n],n*2^Length[p],1]],{p,IntegerPartitions[商[n,2]}];s/n!];