A235828 a(1)=1; a(n+1) is the smallest number, not already used, containing two digits whose difference is the smallest digit of a(n).

1, 10, 11, 12, 21, 23, 13, 32, 20, 22, 24, 31, 34, 14, 43, 25, 35, 30, 33, 36, 41, 45, 15, 54, 26, 42, 46, 37, 47, 40, 44, 48, 51, 56, 16, 65, 27, 53, 52, 57, 38, 58, 49, 59, 50, 55, 61, 67, 17, 76, 28, 64, 62, 68, 39, 63, 69, 60, 66, 71, 78, 18, 87, 29, 75, 72, 79, 70, 77, 81, 89, 19, 98, 80, 88, 91, 100

Offset

1,2

Links

Hans Havermann, Table of n, a(n) for n = 1..1000

Eric Angelini, Smallest digit makes the difference

E. Angelini, Smallest digit makes the difference [Cached copy, with permission]

Example

a(2) = 10 because it is the smallest number containing two digits whose difference is 1.
a(3) = 11 because it is the smallest number containing two digits whose difference is 0.

Mathematica

A = {1}; Do[d = Min@IntegerDigits@Last@A; k = 10; While[MemberQ[A, k] || ! MemberQ[ Abs[ Subtract @@@ Subsets[IntegerDigits@k, {2}]], d], k++]; AppendTo[A, k], {99}]; A (* Giovanni Resta, Jan 16 2014 *)

Crossrefs

Sequence in context: A154328 A112654 A362987 * A102695 A252481 A308854

Adjacent sequences: A235825 A235826 A235827 * A235829 A235830 A235831

Keyword

nonn,base

Author

Eric Angelini, Jan 16 2014

Status

approved