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A372669
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a(n) = Sum_{j=1..n} Sum_{k=1..n} phi(n*j*k) / phi(n*k).
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1
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1, 6, 16, 37, 62, 121, 154, 256, 339, 499, 560, 884, 910, 1308, 1516, 1870, 1979, 2889, 2756, 3776, 4023, 4814, 4795, 6716, 6330, 7908, 8301, 9946, 9520, 13406, 11587, 14598, 15236, 17508, 17438, 22182, 19518, 24329, 24855, 29063, 26521, 35789, 30577, 37769
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Table[Sum[EulerPhi[n*j*k] / EulerPhi[n*k], {j, 1, n}, {k, 1, n}], {n, 1, 50}] (* Vaclav Kotesovec, May 10 2024 *)
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PROG
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(PARI) a(n) = sum(j=1, n, sum(k=1, n, eulerphi(n*j*k)/eulerphi(n*k)));
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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