%I #11 May 15 2022 23:49:10
%S 1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,
%U 0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1
%N a(n) = 1 if n is a power of prime with an even exponent, otherwise 0.
%H Antti Karttunen, <a href="/A353800/b353800.txt">Table of n, a(n) for n = 1..100489</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%H <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>
%F a(n) = A010055(n) - A353817(n).
%F a(n) >= A302048(n).
%e a(1) = 1 because 1 = p^0 for any prime p, and 0 is an even number.
%t a[n_] := If[n == 1 || (Length[(f = FactorInteger[n])] == 1 && EvenQ[f[[1, 2]]]), 1, 0]; Array[a, 100] (* _Amiram Eldar_, May 15 2022 *)
%o (PARI) A353800(n) = ((1==n)||((n=isprimepower(n))&&!(n%2)));
%Y Characteristic function of A056798.
%Y Cf. A010055, A302048, A353817.
%K nonn
%O 1
%A _Antti Karttunen_, May 15 2022