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%I #11 May 06 2022 13:13:51
%S 1,2,3,15,35,33,65,215,221,551,455,2001,3417,3621,11523,16705,16617,
%T 69845,107545,157285,324569,358883,1404949,1569295,3783970,3106285,
%U 7536065,12216295,10589487,24038979,57759065,51961945,177005465,131462695,741703701,1467144445
%N a(n) is the least number k such that the continued fraction for phi(k)/k contains exactly n elements.
%C a(n) is the least number k such that A342866(k) = n.
%C All the terms above 3 are composite numbers.
%F a(2) = 2 since 2 is the least number k such that A342866(k) = 2.
%t f[n_] := Length @ ContinuedFraction[EulerPhi[n]/n]; seq[max_] := Module[{s = Table[0, {max}], c = 0, n = 1, i}, While[c < max, i = f[n]; If[i <= max && s[[i]] == 0, c++; s[[i]] = n]; n++]; s]; seq[20]
%o (PARI) a(n) = my(k=1); while (#contfrac(eulerphi(k)/k) != n, k++); k; \\ _Michel Marcus_, Mar 30 2021
%Y Cf. A000010, A007694, A076512, A109395, A342866.
%Y Cf. A071865 (similar, with sigma(k)/k).
%K nonn
%O 1,2
%A _Amiram Eldar_, Mar 27 2021