A239217 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, 10, 11, 20, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 30, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 40, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 50, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 60, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 70, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 80, 78, 79, 81, 82, 83, 84, 85, 86, 87, 88, 90, 89, 91, 92, 93, 94, 95, 96, 97, 98, 99, 101, 102, 103, 104, 105, 106, 107, 108, 109

Offset

1,2

Comments

Computed by Lars Blomberg.

More than the usual number of terms are displayed, in order to show the difference from A130571. Differs from A130571 at index 91: a(91) = 91, while A130571(91) = 100.

References

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

Links

Table of n, a(n) for n=1..108.

Eric Angelini, Less than <, Equal to =, Greater than > (see sequence St)

Eric Angelini, Less than <, Equal to =, Greater than > [Cached copy, with permission of the author]

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, 108] (* Giorgos Kalogeropoulos, May 13 2022 *)

Crossrefs

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

Cf. A130571.

Sequence in context: A033000 A130573 A032980 * A130571 A275512 A332144

Adjacent sequences: A239214 A239215 A239216 * A239218 A239219 A239220

Keyword

nonn,base

Author

Michel Marcus and N. J. A. Sloane, Mar 12 2014

Status

approved