%I
%S 1,3,9,21,45,117,297,585,1521,3105,6993,14553,43653,90885,185925,
%T 397125,847125,1813125,3238725,7556829,17253789,36910365,94571997,
%U 220301277,475043037,47979336637,183450404605,525019294077
%N a(n+1) is the smallest odd m whose cototient equals a(n).
%F a(n) = Min{x, odd : A051953[ a(n1) ]=a(n)}; a(1)=1; a(2)=3, least odd prime; a(n) = Min[ Select[ Range[ a, b ], Equal[ #EulerPhi[ # ], a(n1) ]& ] ].
%e a(5)=45, cototient(45) = 45  Phi(45) = 45  24 = 21 = a(4). This iteration with even numbers might stop, like {1,2,4,6,10} does if the last computed number has no inverse cototient, like 10 which is a noncototient number.
%Y Cf. A005278, A051953.
%K nonn
%O 1,2
%A _Labos Elemer_, Aug 21 2001
%E More terms from _David Wasserman_, Jul 23 2002
%E a(26)a(28) from _Donovan Johnson_, Feb 06 2010
