|
%I #17 Sep 08 2022 08:46:10
%S 1,3,15,255,65535
%N Numbers n such that the multiset of all values of phi of all divisors of n equals the multiset of all proper divisors of n+1 where phi is the Euler totient function (A000010).
%C Numbers n such that {phi(d); d|n} == {d; d|(n+1), d<(n+1)}.
%C Conjecture: next and last term is 4294967295.
%C Sequence differs from A051179, A050474 and A116518.
%e 15 is in the sequence because {phi(d); d|15} == {1, 2, 4, 8} == {d; d|16, d<16}.
%e 2 is not in the sequence because {phi(d); d|2} == {1, 1} but {d; d|2, d<2} == {1}.
%o (Magma) [n: n in [1..100000] | ([EulerPhi(d): d in Divisors(n)]) eq ([d: d in Divisors(n+1) | d lt n+1 ])]
%Y Cf. A000010, A250404.
%K nonn
%O 1,2
%A _Jaroslav Krizek_, Nov 22 2014
|
