A127254 - OEIS

%I #12 Aug 06 2023 03:05:07

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

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

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

%N (0,1) sequence whose zero positions are indexed by twice the odious numbers given by A091855.

%C 0's appear at positions indexed by 2*A091855(n).

%H Antti Karttunen, <a href="/A127254/b127254.txt">Table of n, a(n) for n = 0..65537</a>

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

%t a[n_] := If[EvenQ[n] && EvenQ[IntegerExponent[n/2, 2]] && OddQ[DigitCount[n/2, 2, 1]], 0, 1]; Array[a, 100, 0] (* _Amiram Eldar_, Aug 06 2023 *)

%o (PARI) A127254(n) = if(n%2,1,!(hammingweight(n)%2 && !(valuation(n/2, 2)%2))); \\ After PARI-code in A091855. - _Antti Karttunen_, Nov 02 2018

%Y Row sums of A127253.

%Y Cf. A000069, A091855.

%K nonn,base

%O 0,1

%A _Paul Barry_, Jan 10 2007

%E More terms from _Antti Karttunen_, Nov 02 2018