OFFSET
1,4
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
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 26 2013
STATUS
approved