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A067578 a(n) = Product_{i=1..n} phi(i) * Sum_{i=1..n} 1/phi(i) where phi is the Euler totient function A000010(n). 0

%I

%S 1,2,5,12,52,120,752,3200,19968,84480,863232,3637248,44384256,

%T 275152896,2254307328,18459131904,298743496704,1846819160064,

%U 33568893960192,274421835104256,3340027488632832,33963860494909440,752840786973818880,6146715129678397440,123926213264670720000

%N a(n) = Product_{i=1..n} phi(i) * Sum_{i=1..n} 1/phi(i) where phi is the Euler totient function A000010(n).

%o (PARI) a(n) = prod(i=1, n, eulerphi(i)) * sum(i=1, n, 1/eulerphi(i)); \\ _Michel Marcus_, Jan 09 2021

%Y Cf. A000010, A001088, A028415, A048049.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Jan 30 2002

%E More terms from _Michel Marcus_, Jan 09 2021

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Last modified April 20 01:55 EDT 2021. Contains 343118 sequences. (Running on oeis4.)