%I #9 Jan 01 2024 15:06:21

%S 1,23,32,456,465,546,564,645,654,10789,10798,10879,10897,10978,10987,

%T 17089,17098,17809,17890,17908,17980,18079,18097,18709,18790,18907,

%U 18970,19078,19087,19708,19780,19807,19870,70189,70198,70819,70891

%N Numbers in ascending order formed by using all the digits of the next n numbers.

%C The next four numbers are 7,8,9 and 10 and hence the next terms are all the numbers formed by the digits 1,0,7,8 and 9 in ascending order.

%H Harvey P. Dale, <a href="/A081991/b081991.txt">Table of n, a(n) for n = 1..5000</a>

%e The next two numbers are 2 and 3 and the two numbers that can be formed are 23 and 32 hence a(2) = 23 and a(3) = 32.

%t uad[l_]:=Module[{d=Flatten[IntegerDigits/@l],len},len=Length[d];Select[FromDigits/@ Permutations[ d],IntegerLength[#]==len&]//Sort]; uad/@With[{nn=4},TakeList[Range[ (nn(nn+1))/2],Range[nn]]]//Flatten (* _Harvey P. Dale_, Jan 01 2024 *)

%Y Cf. A081992, A081993.

%K base,nonn

%O 1,2

%A _Amarnath Murthy_, Apr 05 2003

%E More terms from _David Wasserman_, Jul 27 2004