%I #9 Jul 07 2024 08:02:02

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

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

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

%N a(n) = 1 if n is odd and the cyclotomic polynomial Phi(k,x) has height 1, i.e., is flat, otherwise 0. Here flat means that the coefficients of a polynomial are all -1, 0, or 1.

%H Antti Karttunen, <a href="/A374136/b374136.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) A374136(n) = (n%2 && 1==vecmax(abs(Vec(polcyclo(n)))));

%Y Characteristic function of A374137.

%Y Differs from A000035 first at n=105, where a(105) = 0, while A000035(105) = 1.

%Y Differs from A374134 first at n=255, where a(255) = 0, while A374134(255) = 1.

%K nonn

%O 1

%A _Antti Karttunen_, Jul 06 2024