This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A297062 #14 Jan 02 2018 15:54:46 %S A297062 0,1,10,102,120,201,210,1023,1032,1203,1230,1302,1320,2013,2031,2103, %T A297062 2130,2301,2310,3012,3021,3102,3120,3201,3210,10234,10243,10324,10342, %U A297062 10423,10432,12034,12043,12304,12340,12403,12430,13024,13042,13204,13240,13402,13420,14023 %N A297062 Starting with a(1) = 0, a(2) = 1, a(n) = smallest nonnegative integer that shares all digits with previous terms. No repeated digits are allowed. %C A297062 With the restriction that no repeated digits are allowed, the sequence is finite and contains 10! + 1 terms. (Proof: The number of terms of length n is equal to n! - (n-1)! for 2 <= n <= 10. Then the sum is telescopic, yielding 10! - 1!. Adding the 2 initial terms we get the result.) The smallest 10-digit term is 1023456789 and the last term of the sequence is 9876543210. %t A297062 Nest[Function[a, Append[a, Block[{k = Last@ a + 1}, While[Nand[Union@ Tally[#][[All, -1]] == {1}, Complement[Union@ Flatten@ Map[IntegerDigits, a], #] == {}] &@ IntegerDigits@ k, k++]; k]]], {0, 1}, 42] (* _Michael De Vlieger_, Dec 24 2017 *) %Y A297062 Cf. A199168. %K A297062 nonn,base %O A297062 1,3 %A A297062 _Enrique Navarrete_, Dec 24 2017