$RecursionLimit=无穷大;z=400;v[1]=0;v[2]=1;
v[n_u]:=v[n]=v[n-1]/(n-2)+v[n-2];
TableForm[表[{n,n[Pi-(4 n+2)/(v[2(n+1)]^2)],n[1/n]},{n,1,10}]]
g[n_x]:=g[n]=选择[范围[z],Pi-(4#+2)/(v[2(#+1)]^2)<1/n&,1];
u=展平[表[g[n],{n,1,z}]](*A247973号*)
d=差异[u]
展平[位置[d,0]](*A247974号*)
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