cp's OEIS Frontend

A039643 Number of steps to fixed point of "k -> k/2 or (k-1)/2 until result is prime", starting with prime(n)+1.

%I A039643 #11 Aug 08 2025 03:23:31
%S A039643 1,2,2,3,3,2,4,3,4,3,5,2,4,3,5,3,4,2,3,6,2,5,5,4,6,6,4,4,4,5,7,7,4,4,
%T A039643 3,4,2,3,6,3,5,5,7,2,7,7,3,6,6,6,4,6,6,4,8,8,3,5,2,5,3,3,5,5,2,3,3,7,
%U A039643 4,4,6,6,5,5,4,8,3,2,8,8,6,2,6,6,6,6,7,2,7,5,5,7,4,4,5,5,3,9,3,2,3,3
%N A039643 Number of steps to fixed point of "k -> k/2 or (k-1)/2 until result is prime", starting with prime(n)+1.
%H A039643 Reinhard Zumkeller, <a href="/A039643/b039643.txt">Table of n, a(n) for n = 1..10000</a>
%t A039643 (* See A039636. *)
%o A039643 (Haskell)
%o A039643 a039643 n = snd $ until ((== 1) . a010051 . fst)
%o A039643                   (\(x, i) -> (x `div` 2 , i + 1)) (a000040 n + 1, 1)
%o A039643 -- _Reinhard Zumkeller_, Nov 17 2013
%Y A039643 Cf. A039634-A039645.
%Y A039643 Cf. A010051, A000040, A039639, A039645, A039636.
%K A039643 nonn
%O A039643 1,2
%A A039643 _Wouter Meeussen_
%E A039643 Offset corrected by _Reinhard Zumkeller_, Nov 17 2013