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Table of n, a(n) for n=1..99.
G. Niklasch, Some number theoretical constants: 1000-digit values [Cached copy]
Eric Weisstein's World of Mathematics, Totient Summatory Function
Cf. A065484, A078074.
Sequence in context: A156164 A198613 A197031 * A019745 A173815 A188615
Adjacent sequences: A065480 A065481 A065482 * A065484 A065485 A065486
N. J. A. Sloane, Nov 19 2001