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%I #13 Jun 01 2022 18:08:58
%S 1,1,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,0,
%T 0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,1,0,1,0,1,0,0,0,1,0,1,0,0,
%U 0,1,0,1,0,0,0,0,0,1,0,1,0,1,0,1,0,0
%N Characteristic function of A002202, the range of Euler's totient function A000010.
%H Reinhard Zumkeller, <a href="/A264739/b264739.txt">Table of n, a(n) for n = 1..10000</a>
%F a(A002202(n)) = 1 and a(A007617(n)) = 0.
%F More precisely: a(n) = 1 <=> n in A002202 <=> n is not in A007617. - _M. F. Hasler_, Aug 13 2021
%o (Haskell)
%o import Data.List.Ordered (has)
%o a264739 n = if a002202_list `has` n then 1 else 0
%o (PARI) apply( A264739=istotient, [1..99]) \\ _M. F. Hasler_, Aug 13 2021
%Y Cf. A000010, A002202, A007617, A264810 (partial sums), A180639.
%K nonn
%O 1
%A _Reinhard Zumkeller_, Nov 26 2015
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