A372447 - OEIS

%I #5 May 03 2024 15:41:18

%S 4,5,4,5,6,6,7,6,6,7,6,7,7,7,8,8,9,8,7,7,8,8,8,8,8,9,10,10,11,9,10,11,

%T 11,9,8,8,5,4,5,5,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

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

%N a(n) = A000523(A372443(n)); One less than the binary length of the n-th iterate of 27 with Reduced Collatz-function R.

%H <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a>

%o (PARI)

%o A000265(n) = (n>>valuation(n,2));

%o A000523(n) = logint(n,2);

%o A372443(n) = { my(x=27); while(n, x=A000265(3*x+1); n--); (x); };

%o A372447(n) = A000523(A372443(n));

%Y Cf. A000523, A372443.

%K nonn

%O 0,1

%A _Antti Karttunen_, May 03 2024