%I #13 Apr 16 2023 13:41:16
%S 1,2,3,4,5,6,7,8,9,20,31,40,51,60,71,80,91,200,311,400,511,600,711,
%T 800,911,2000,3111,4000,5111,6000,7111,8000,9111,20000,31111,40000,
%U 51111,60000,71111,80000,91111,200000,311111,400000,511111,600000,711111,800000,911111,2000000
%N Lexicographically earliest increasing sequence of numbers with all odd digits alternating with numbers with all even digits.
%H Harvey P. Dale, <a href="/A180412/b180412.txt">Table of n, a(n) for n = 1..1000</a>
%e 11 is all odd digits. The next number in which all of the digits are even is 20. The next number in which all of the digits are odd is 31.
%t nxt[n_]:=Module[{fidn=First[IntegerDigits[n]],len=IntegerLength[n]},Which[fidn==9,2*10^len, EvenQ[ fidn], FromDigits[PadRight[{fidn+1},len,1]],OddQ[fidn],FromDigits[PadRight[ {fidn+ 1}, len,0]]]]; NestList[nxt,1,50] (* _Harvey P. Dale_, Nov 26 2013 *)
%Y Cf. A014261, A014263.
%K easy,nonn,base
%O 1,2
%A _Dominick Cancilla_, Sep 02 2010
%E Name edited by _Michel Marcus_, Apr 16 2023
|