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
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]
Crossrefs
Programs
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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 *)
Comments