login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Parity of A038548, where A038548(n) is the number of divisors of n that are at most sqrt(n).
3

%I #7 Jan 24 2024 18:32:38

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

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

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

%N Parity of A038548, where A038548(n) is the number of divisors of n that are at most sqrt(n).

%C Also parity of the Möbius transform of A369255.

%H Antti Karttunen, <a href="/A369253/b369253.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) = A000035(A038548(n)).

%o (PARI) A369253(n) = (sumdiv(n,d,1-(bigomega(d)%2))%2);

%Y Characteristic function of A369254.

%Y Cf. A000035, A065043, A038548, A369255.

%K nonn

%O 1

%A _Antti Karttunen_, Jan 24 2024