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%I #11 Jun 13 2022 16:47:20
%S 1,1,1,1,1,1,1,1,1,1,1,0,1,1,0,1,1,0,1,0,0,1,1,0,1,1,1,0,1,0,1,1,0,1,
%T 0,0,1,1,0,0,1,0,1,0,0,1,1,0,1,0,0,0,1,0,0,0,0,1,1,0,1,1,0,1,0,0,1,0,
%U 0,0,1,0,1,1,0,0,0,0,1,0,1,1,1,0,0,1,0,0,1,0,0,0,0,1,0,0,1,0,0,0,1,0,1,0,0,1,1,0,1,0,0,0,1,0,0,0,0,1,0,0,1
%N a(n) = 1 if n is either a power of prime or 2*prime, otherwise 0.
%H Antti Karttunen, <a href="/A354923/b354923.txt">Table of n, a(n) for n = 1..100000</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F For n > 4, a(n) = A010055(n) + A353478(n).
%t a[n_] := If[PrimePowerQ[n] || PrimeQ[n/2], 1, 0]; a[1] = 1; Array[a, 100] (* _Amiram Eldar_, Jun 13 2022 *)
%o (PARI) A354923(n) = ((1==n)|| isprimepower(n) || (!(n%2) && isprime(n/2)));
%Y Characteristic function of A354925.
%Y Cf. A010055, A265128, A353478.
%Y Cf. also A354924.
%K nonn
%O 1
%A _Antti Karttunen_, Jun 13 2022
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