A275782 a(n) = smallest k such that the digits of exactly n nonnegative numbers are a subsequence of the digits of k.

0, 11, 10, 100, 101, 102, 120, 1002, 1022, 1012, 1021, 1023, 1201, 1203, 1230, 10023, 10121, 10120, 10201, 10123, 10232, 10213, 10231, 10234, 12132, 12013, 12031, 12034, 12301, 12304, 12340, 100234, 101201, 101213, 101232, 101203, 101231, 101230, 102031, 101234, 102132, 102130, 102301, 102134, 102342

Offset

1,2

Links

David W. Wilson, Table of n, a(n) for n = 1..1024

Example

The digits of exactly 19 numbers are a subsequence of 10201: 0, 1, 2, 10, 11, 12, 20, 21, 100, 101, 102, 120, 121, 201, 1001, 1020, 1021, 1201, and 10201. No number smaller than 10201 has this property. Hence a(19) = 10201.

Mathematica

t = Table[Length@ Union@ Map[FromDigits, Subsets@ IntegerDigits@ n /. {} -> Nothing], {n, 0, 103000}]; Table[FirstPosition[t, n] - 1, {n, Max@ t}] // Flatten (* Michael De Vlieger, Aug 08 2016, Version 10.2 *)

Crossrefs

Sequence in context: A061882 A323296 A373693 * A120005 A362335 A105026

Adjacent sequences: A275779 A275780 A275781 * A275783 A275784 A275785

Keyword

nonn,base

Author

David W. Wilson, Aug 08 2016

Status

approved