A239085 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, 90, 11, 10, 12, 20, 13, 30, 14, 40, 15, 50, 16, 60, 17, 70, 18, 80, 19, 91, 22, 21, 23, 31, 24, 41, 25, 51, 26, 61, 27, 71, 28, 81, 29, 92, 33, 32, 34, 42, 35, 52, 36, 62, 37, 72, 38, 82, 39, 93, 44, 43, 45, 53, 46, 63, 47, 73, 48, 83, 49, 94, 55, 54, 56, 64, 57, 74, 58, 84, 59, 95, 66, 65, 67, 75, 68, 85, 69, 96, 77, 76

Offset

1,2

Comments

Computed by Lars Blomberg.

References

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

Links

Table of n, a(n) for n=1..90.

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

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[s[[-2;; ]], {k}]], 3, 1]), k++]; k]; Array[a, 90] (* Giorgos Kalogeropoulos, May 14 2022 *)

Crossrefs

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

Sequence in context: A208130 A160343 A250265 * A273478 A278944 A303171

Adjacent sequences: A239082 A239083 A239084 * A239086 A239087 A239088

Keyword

nonn,base

Author

N. J. A. Sloane, Mar 10 2014

Status

approved