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a(n) = lcm(1,2,3,...,n) * (sum of Farey fractions of order n).
0

%I #14 Mar 05 2023 05:50:53

%S 1,3,15,42,330,390,3990,9660,36540,41580,595980,651420,10630620,

%T 11711700,13153140,29189160,594233640,630990360,14083949880,

%U 15015120120,16411875480,17575838280,463140798120,484557713640,2690500012200

%N a(n) = lcm(1,2,3,...,n) * (sum of Farey fractions of order n).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FareySequence.html">Farey Sequence</a>.

%F a(n) = A093593(n)/A025527(n).

%t Farey[n_] := Union[ Flatten[ Join[{0}, Table[a/b, {b, n}, {a, b}]]]]; Table[LCM @@ Range[n] Plus @@ Farey[n], {n, 26}]

%Y Cf. A025527, A093593.

%K nonn

%O 1,2

%A _Robert G. Wilson v_ and _Clark Kimberling_, Apr 06 2004