A135534 - OEIS

%I #13 Jul 06 2022 19:40:16

%S 1,3,0,7,0,1,0,15,0,1,0,3,0,1,0,31,0,1,0,3,0,1,0,7,0,1,0,3,0,1,0,63,0,

%T 1,0,3,0,1,0,7,0,1,0,3,0,1,0,15,0,1,0,3,0,1,0,7,0,1,0,3,0,1,0,127,0,1,

%U 0,3,0,1,0,7,0,1,0,3,0,1,0,15,0,1,0,3,0,1,0,7,0,1,0,3,0,1,0,31,0,1,0,3,0,1

%N a(1) = 1; for n>=1, a(2n) = A135561(n), a(2n+1) = 0.

%H Antti Karttunen, <a href="/A135534/b135534.txt">Table of n, a(n) for n = 1..65537</a>

%p GS(6,1,200); [see A135416].

%o (PARI)

%o A135560(n) = { my(t=valuation(n, 2)); (t + (n==2^t) + 1); }; \\ From A135560

%o A135534(n) = if(1==n,1,if((n%2),0,((2^(A135560(n/2)))-1))); \\ _Antti Karttunen_, Sep 27 2018

%o (Python)

%o def A135534(n): return 1 if n == 1 else 0 if n&1 else (1<<(m:=(~(k:=n>>1) & k-1)).bit_length()+int(m==k-1)+1)-1 # _Chai Wah Wu_, Jul 06 2022

%Y Cf. A135416.

%Y This is Guy Steele's sequence GS(6, 1) (see A135416).

%K nonn

%O 1,2

%A _N. J. A. Sloane_, based on a message from Guy Steele and _Don Knuth_, Mar 01 2008