%I #10 Jan 10 2018 12:31:36

%S 1,9,10,81,90,100,729,810,900,1000,6561,7290,8100,9000,10000,59049,

%T 65610,72900,81000,90000,100000,531441,590490,656100,729000,810000,

%U 900000,1000000,4782969,5314410,5904900,6561000,7290000,8100000,9000000

%N Numbers of form 9^i*10^j, with i, j >= 0.

%H Reinhard Zumkeller, <a href="/A025635/b025635.txt">Table of n, a(n) for n = 1..10000</a>

%o (Haskell)

%o import Data.Set (singleton, deleteFindMin, insert)

%o a025635 n = a025635_list !! (n-1)

%o a025635_list = f $ singleton (1,0,0) where

%o f s = y : f (insert (9 * y, i + 1, j) $ insert (10 * y, i, j + 1) s')

%o where ((y, i, j), s') = deleteFindMin s

%o -- _Reinhard Zumkeller_, May 15 2015

%o (PARI) list(lim)=my(v=List(), N); for(n=0, logint(lim\=1, 10), N=10^n; while(N<=lim, listput(v, N); N*=9)); Set(v) \\ _Charles R Greathouse IV_, Jan 10 2018

%Y Cf. A025612, A025616, A025621, A025625, A025629, A025632, A025634, A108761, A003596, A003597, A107988, A003598, A108698, A003599, A107788, A108687, A108779, A108090.

%K easy,nonn

%O 1,2

%A _David W. Wilson_