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A217921
Number of steps to calculate A175872(n).
2
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
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
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 26 2013
STATUS
approved