A373260 - OEIS

%I #6 May 30 2024 18:48:41

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

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

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

%N a(n) = 1 if A276085(n) == +1 (mod 3), otherwise 0, where A276085 is the primorial base log-function.

%H Antti Karttunen, <a href="/A373260/b373260.txt">Table of n, a(n) for n = 1..100000</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%o (PARI)

%o A002110(n) = prod(i=1,n,prime(i));

%o A276085(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2]*A002110(primepi(f[k, 1])-1)); };

%o A373260(n) = (1==(A276085(n)%3));

%Y Characteristic function of A373261.

%Y Cf. A002110, A276085, A373153.

%K nonn

%O 1

%A _Antti Karttunen_, May 30 2024