A217921 Number of steps to calculate A175872(n).

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, 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, 4, 2, 3, 2, 2, 4, 5, 3, 4, 2, 2, 3, 4, 3, 3, 3, 1, 4

Offset

1,4

Comments

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

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Example

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;
n=127, no step: [1,1,1,1,1,1,1], therefore a(127)=0, A175872(127)=7;
n=128, 2 steps: [1,0,0,0,0,0,0,0]->[1,7]->[1,1], therefore a(128)=2, A175872(128)=2;
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;
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;
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.

Prog

(Haskell)
import Data.List (group, genericLength)
a217921 n = fst $ until (all (== 1) . snd) f (0, a030308_row n) where
   f (i, xs)  = (i + 1, map genericLength $ group xs)

Crossrefs

Cf. A030308.

Sequence in context: A118207 A327274 A055378 * A272328 A334956 A335881

Adjacent sequences: A217918 A217919 A217920 * A217922 A217923 A217924

Keyword

nonn

Author

Reinhard Zumkeller, Mar 26 2013

Status

approved