

A039777


Integers m such that phi(m) is equal to the sum of (the product of prime factors) and (the product of exponents) of m1.


0



2, 5, 21, 45, 285, 765, 27645, 196605, 41067645, 72787965, 250871805, 4295098365, 12884901885, 23307153405, 172130669565, 1766029428523005, 20978888016396285
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OFFSET

1,1


COMMENTS

No other terms below 10^24. Some large terms: 1039619980803100740810795122685, 32576974833437288924302842789885.  Max Alekseyev, Jul 28 2024
All listed terms represent solutions to phi(m) = (m+3)/2 such that (m1)/2 is an even squarefree number. Cf. A350777.  Max Alekseyev, Jul 21 2024
a(1)=2 is the only even term below 10^100000.  Max Alekseyev, Jul 22 2024


LINKS



EXAMPLE

21 is a term since 211 = 2^2*5^1 and (2*5)+(2*1) = 12 = phi(21).


CROSSREFS



KEYWORD

nonn,more,hard


AUTHOR



EXTENSIONS



STATUS

approved



