

A145680


a(n) = smallest number m such that UnitarySigma(m) = nm/(n1).


1



6, 2, 3, 4, 5, 216, 7, 8, 9, 5292000, 11, 10584000, 13, 4991499040640000, 165375, 16, 17, 235270656, 19, 101867327360000, 8107610881081625211441398582431641600000, 19235716742537891017605454376709022095843377283072000000, 23, 552063590295800832, 25
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OFFSET

2,1


COMMENTS

If n=p^i+1 then a(n)=p^i.
Unitary sigma = A034448 = sum of divisors d with gcd(d,m/d)=1.


LINKS



EXAMPLE

UnitarySigma(216) = 2^2*3^2*7 = (7/6)*216.


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



