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A255309 Number of times log_2 can be applied to n until the result is either 1 or not a power of 2. Here log_2 means the base-2 logarithm.

%I A255309 #24 Jun 13 2022 10:55:20
%S A255309 0,0,1,0,2,0,0,0,1,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,
%T A255309 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,
%U A255309 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1
%N A255309 Number of times log_2 can be applied to n until the result is either 1 or not a power of 2. Here log_2 means the base-2 logarithm.
%H A255309 Antti Karttunen, <a href="/A255309/b255309.txt">Table of n, a(n) for n = 0..65537</a>
%F A255309 a(n) = 1 + a(log_2(n)) if n is a power of 2 except 1, 0 otherwise.
%o A255309 (PARI) nbi(n) = {my(nb = 0); if ((ispower(n, ,&m) && (m==2)) || (n==2), return(nbi(valuation(n, 2))+1);); nb;}
%o A255309 a(n) = { my(nb = 0); if ((ispower(n, ,&m) && (m==2)) || (n==2), return(nbi(valuation(n, 2))+1);); nb;} \\ _Michel Marcus_, Mar 11 2015; corrected Jun 13 2022
%o A255309 (PARI) A255309(n) = { my(k=0); while((n>1)&&!bitand(n,n-1),n = valuation(n,2); k++); (k); }; \\ _Antti Karttunen_, Sep 30 2018
%Y A255309 Cf. A000079 (2^n), A007814 (2-adic valuation of n), A209229, A255308.
%K A255309 nonn,easy
%O A255309 0,5
%A A255309 _Paul Boddington_, Feb 20 2015
%E A255309 Extended up to a(128) by _Antti Karttunen_, Sep 30 2018