A353479 - OEIS

%I #17 Apr 22 2022 10:40:42

%S 0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

%T 1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,

%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,1,0

%N a(n) = 1 if n is a semiprime of the form 4k+3, otherwise 0.

%H Antti Karttunen, <a href="/A353479/b353479.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) == 3], where [ ] are the Iverson brackets.

%F a(n) = A353480(n) - A353477(n).

%F a(n) = A280710(n) * A342025(n) = A353480(n) * A342025(n).

%o (PARI) A353479(n) = ((2==bigomega(n)) && (3==(n%4)));

%Y Characteristic function of A080774.

%Y Cf. A001222, A010873, A064911, A280710, A342025, A353477, A353478, A353480.

%K nonn

%O 1

%A _Antti Karttunen_, Apr 22 2022