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%I #7 May 09 2024 06:59:13
%S 1,7,14,28,41,63,82,112,137,175,206,252,289,343,386,448,497,567,622,
%T 700,761,847,914,1008,1081,1183,1262,1372,1457,1575,1666,1792,1889,
%U 2023,2126,2268,2377,2527,2642,2800,2921,3087,3214,3388,3521,3703,3842,4032,4177,4375
%N a(n) = Sum_{j=1..n} Sum_{k=1..n} phi(2*j*k) / phi(j*k).
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TotientFunction.html">Totient Function</a>.
%t Table[Sum[Sum[EulerPhi[2*j*k]/EulerPhi[j*k], {j, 1, n}], {k, 1, n}], {n, 1, 50}] (* _Vaclav Kotesovec_, May 09 2024 *)
%o (PARI) a(n) = sum(j=1, n, sum(k=1, n, eulerphi(2*j*k)/eulerphi(j*k)));
%Y Cf. A000010, A372664.
%K nonn
%O 1,2
%A _Seiichi Manyama_, May 09 2024