A239215 The sequence S = a(1), a(2), ... is defined by a(1)=1, if d,e,f are consecutive digits then we do not have d >= e > f, and S is always extended with the smallest integer not yet present in S.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 23, 24, 25, 26, 27, 28, 29, 33, 34, 35, 36, 37, 38, 39, 44, 45, 46, 47, 48, 49, 55, 56, 57, 58, 59, 66, 67, 68, 69, 77, 78, 79, 88, 89, 99, 999, 9999, 99999, 999999, 9999999, 99999999

Offset: 1

Author

Michel Marcus, Mar 12 2014

Keywords

• nonn
• base

Comments

Computed by Lars Blomberg.

References

• Eric Angelini, Posting to Sequence Fans Mailing List, Sep 28 2013

Links

• Eric Angelini, Less than <, Equal to =, Greater than > (see sequence Sr)
• Eric Angelini, Less than <, Equal to =, Greater than > [Cached copy, with permission of the author]

Crossrefs

The sequences in this family are given in A239083-A239086, A239136-A239139, A239087-A239090, A239215-A239218, A239235.

Programs

Mathematica

a[1]=1;a[n_]:=a[n]=Block[{k=1},While[MemberQ[s=Array[a,n-1],k]||Or@@(#>=#2>#3&@@@Partition[Flatten[IntegerDigits/@Join[Last@s,{k}]],3,1]),k++];k];Array[a,56] (* Giorgos Kalogeropoulos, May 13 2022 *)