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A217921 Number of steps to calculate A175872(n). 2

%I

%S 0,1,0,2,1,2,0,2,2,1,3,3,3,2,0,2,2,4,3,3,1,4,3,2,3,3,2,2,3,2,0,2,2,4,

%T 2,2,4,3,2,3,4,1,3,4,3,4,3,2,2,4,3,3,3,2,2,3,2,3,2,2,3,2,0,2,2,4,2,2,

%U 4,2,3,2,2,4,5,3,4,2,2,3,4,3,3,3,1,4

%N Number of steps to calculate A175872(n).

%C a(A000225(n)) = 0; a(A000975(n)) = 1.

%H Reinhard Zumkeller, <a href="/A217921/b217921.txt">Table of n, a(n) for n = 1..10000</a>

%e n=100, 4 steps: [1,1,0,0,1,0,0]->[2,2,1,2]->[2,1,1]->[1,2]->[1,1], therefore a(100)=4, A175872(100)=2;

%e n=127, no step: [1,1,1,1,1,1,1], therefore a(127)=0, A175872(127)=7;

%e n=128, 2 steps: [1,0,0,0,0,0,0,0]->[1,7]->[1,1], therefore a(128)=2, A175872(128)=2;

%e n=129, 2 steps: [1,0,0,0,0,0,0,1]->[1,6,1]->[1,1,1], therefore a(129)=2, A175872(129)=3;

%e n=130, 4 steps: [1,0,0,0,0,0,1,0]->[1,5,1,1]->[1,1,2]->[2,1]->[1,2], therefore a(130)=4, A175872(130)=2;

%e n=131, 2 steps: [1,0,0,0,0,0,1,1]->[1,5,2]->[1,1,1], therefore a(131)=2, A175872(100)=3.

%o (Haskell)

%o import Data.List (group, genericLength)

%o a217921 n = fst $ until (all (== 1) . snd) f (0, a030308_row n) where

%o f (i, xs) = (i + 1, map genericLength $ group xs)

%Y Cf. A030308.

%K nonn

%O 1,4

%A _Reinhard Zumkeller_, Mar 26 2013

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Last modified April 20 20:26 EDT 2021. Contains 343137 sequences. (Running on oeis4.)