a[1]=1;a[n_]:=a[n]=1+a[n-1]+合计[Product[二项式[a[i]-1+计数[#,i],计数[#、i]],{i,DeleteCases[DeleteDuplicates[#],1]}]&/@IntegerPartitions[n,{2,n-1}]];(*A108521号*)
b[1]=1;b[n_]:=b[n]=如果[n>2,1,0]+如果[EvenQ[n],a[n/2](a[n/2]+1)/2,a[(n-1)/2](a[(n-1)/2]+1)/2]+如果[n>3,总计[If[Max[#]<=如果[Even Q[n]n,n/2-1,(n-1 DeleteDuplicates[#],1]}],0]&/@IntegerPartitions[n,{3,n-1}]],0];
表[b[n],{n,40}]
(*a[n])=A108521号[n] ;d[n]是g.f.*中A^2(x)的系数
a[0]=0;a[1]=1;a[n]:=a[n]=a[n-1]+(除数和[n,a[#]#&,#<n&]+和[c[k]b[n-k],{k,n-1}])/n;b[n]:=b[n]=(c[n]+和[c[k]b[n-k],{k,n-1}])/n;c[n_]:=c[n]=除数和[n,a[#]#&];d[n_]:=d[n]=总和[2a[k]a[n-k],{k,Floor[(n-1)/2]}]+如果[EvenQ[n],a[n/2]^2,0];表[a[n]-d[n]+(d[n-1]+如果[OddQ[n],a[(n-1)/2],0])/2,{n,40}]
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