A359150 - OEIS

%I #11 Dec 17 2022 22:53:35

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

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

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

%N a(n) = 1 if n is a number of the form 4u+1 with an odd number of prime factors (counted with multiplicity), otherwise 0.

%H Antti Karttunen, <a href="/A359150/b359150.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 a(n) = A066829(n) * A121262(n-1).

%F a(n) = A353558(n) - A359152(n).

%F a(n) = A121262(n-1) - A359160(n).

%F a(n) >= A358678(n).

%o (PARI) A359150(n) = ((bigomega(n)%2)&&(1==(n%4)));

%Y Characteristic function of A359151.

%Y Cf. A066829, A121262, A353558, A359152, A359160.

%Y Differs from A358678 for the first time at n=105, where a(105) = 1, while A358678(105) = 0.

%K nonn

%O 1

%A _Antti Karttunen_, Dec 17 2022