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%I #19 Apr 19 2016 01:10:16
%S 6,2,3,4,5,216,7,8,9,5292000,11,10584000,13,4991499040640000,165375,
%T 16,17,235270656,19,101867327360000,
%U 8107610881081625211441398582431641600000,19235716742537891017605454376709022095843377283072000000,23,552063590295800832,25
%N a(n) = smallest number m such that UnitarySigma(m) = nm/(n-1).
%C If n=p^i+1 then a(n)=p^i.
%C Unitary sigma = A034448 = sum of divisors d with gcd(d,m/d)=1.
%C Note that a(27) > 10^70. - _Jack Brennen_, Feb 04 2014
%e UnitarySigma(216) = 2^2*3^2*7 = (7/6)*216.
%Y Cf. A034448.
%Y Related sequences include A145681 (and A144672, A144673, A144674) for 3/2-URPMS, and A144949-A144951 for 5/4-URPMS. - _M. F. Hasler_, Jan 29 2014
%K nonn
%O 2,1
%A _Yasutoshi Kohmoto_ Mar 09 2009
%E Corrected a(13) and added a(22) found by _Jack Brennen_. _M. F. Hasler_, Feb 04 2014
%E a(23)-a(26) from _Jack Brennen_, Feb 04 2014