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A332686
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a(n) = Sum_{k=1..n} phi(k/gcd(n, k)).
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2
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1, 2, 3, 5, 7, 9, 13, 18, 21, 23, 33, 33, 47, 49, 51, 67, 81, 76, 103, 97, 103, 119, 151, 135, 163, 173, 185, 189, 243, 185, 279, 280, 265, 299, 291, 291, 397, 379, 369, 371, 491, 381, 543, 491, 455, 553, 651, 539, 653, 610, 643, 683, 831, 689, 743, 753, 801, 887, 1029
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OFFSET
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1,2
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COMMENTS
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Inverse Moebius transform of A053570.
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LINKS
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Seiichi Manyama, Table of n, a(n) for n = 1..10000
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FORMULA
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a(n) = Sum_{k=1..n} phi(lcm(n, k)/n).
a(n) = Sum_{d|n} A053570(d).
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MATHEMATICA
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Table[Sum[EulerPhi[k/GCD[n, k]], {k, 1, n}], {n, 1, 59}]
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PROG
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(PARI) a(n) = sum(k=1, n, eulerphi(k/gcd(n, k))); \\ Michel Marcus, Feb 21 2020
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CROSSREFS
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Cf. A000010, A002088, A029935, A029939, A053570, A332685.
Sequence in context: A302835 A200672 A341497 * A069999 A271661 A035563
Adjacent sequences: A332683 A332684 A332685 * A332687 A332688 A332689
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KEYWORD
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nonn
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AUTHOR
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Ilya Gutkovskiy, Feb 19 2020
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STATUS
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approved
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