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%I #11 Mar 03 2024 15:55:21
%S 0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,1,0,
%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,
%U 1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1
%N a(n) = 1 if n is a semiprime of the form 4k+1, otherwise 0.
%H Antti Karttunen, <a href="/A353477/b353477.txt">Table of n, a(n) for n = 1..65537</a>
%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
%F a(n) = [A001222(n) == 2] * && [A010873(n) == 1], where [ ] are the Iverson brackets.
%F a(n) = A353480(n) - A353479(n).
%t Table[If[PrimeOmega[n]==2&&Mod[n,4]==1,1,0],{n,130}] (* _Harvey P. Dale_, Mar 03 2024 *)
%o (PARI) A353477(n) = ((2==bigomega(n)) && (1==(n%4)));
%Y Characteristic function of A108181.
%Y Cf. A001222, A010873, A064911, A353478, A353479, A353480.
%K nonn
%O 1
%A _Antti Karttunen_, Apr 22 2022
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