A153638 - OEIS

%I #2 Mar 30 2012 18:49:09

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

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

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

%N Odiousness of triangular numbers.

%C The odiousness of a number is equal to 1 if the number is odious, meaning that it has an odd number of ones in its binary expansion. Otherwise, it is zero.

%e a(2) is 0, because the second triangular number is 3, which in binary is 11 and has an even number of ones.

%t od[n_] := Mod[Count[IntegerDigits[n, 2], 1], 2] Table[od[n (n + 1)/2], {n, 0, 128}]

%Y A000217 Triangular numbers.

%K nonn

%O 0,1

%A _Tanya Khovanova_, Dec 29 2008