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Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of m; set a(n) = -1 if some fraction i/n never appears.
3

%I #11 Nov 19 2017 21:58:17

%S 1,2,3,401,113,22,75,401,1986,6547,1110,5949,7952,2445,5578,172617,

%T 2590,1986,17471,41341,13631,20900,14063,121563,86009,17648,392866,

%U 140171,59293,257162,68370,172617,226693,89942,489653,151601,153287,231508,860521,999664,479352,751180,475540,1312350,246470,287004,84285,1137690,363942,86009,276267,603972,219888,1139722,1525515,5227193,1486480,206546,379708,1244626,374003,590152,7230480,1903679,1834403

%N Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of m; set a(n) = -1 if some fraction i/n never appears.

%e 3/4 does not occur until we reach A066720(401) = 2436 and then we see A066720(320)/A066720(401) = 1827/2436 = 3/4. Therefore a(4) = 401.

%Y Cf. A066720, A066657, A066658. A066848 gives values of k.

%K nonn,nice

%O 1,2

%A _N. J. A. Sloane_, Jan 21 2002

%E Corrected by _John W. Layman_, Feb 05 2002

%E Greatly extended by _David Applegate_, Feb 13 2002