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 A072155 Denominator of Sum_{k=1..n} phi(k)/k. 4
 1, 2, 6, 3, 15, 5, 35, 70, 210, 210, 2310, 770, 10010, 10010, 30030, 15015, 255255, 255255, 4849845, 4849845, 4849845, 4849845, 111546435, 37182145, 37182145, 37182145, 111546435, 111546435, 3234846615, 3234846615, 100280245065, 200560490130, 200560490130 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE 1, 3/2, 13/6, 8/3, 52/15, 19/5, 163/35, 361/70, 1223/210, ... MATHEMATICA Table[Sum[EulerPhi[k]/k, {k, n}], {n, 40}]//Denominator (* Harvey P. Dale, Jun 08 2017 *) PROG (PARI) a(n) = denominator(sum(k=1, n, eulerphi(k)/k)); \\ Michel Marcus, Jan 26 2015 CROSSREFS Cf. A071708 (numerators), A250031, A250032, A250034. Sequence in context: A055773 A111866 A251753 * A094299 A304537 A121566 Adjacent sequences:  A072152 A072153 A072154 * A072156 A072157 A072158 KEYWORD nonn,frac AUTHOR N. J. A. Sloane, Jun 28 2002 STATUS approved

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Last modified December 16 07:12 EST 2018. Contains 318158 sequences. (Running on oeis4.)