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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.
0
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
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
KEYWORD
nonn,base
AUTHOR
STATUS
approved