login
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

%I #16 Jul 31 2022 07:45:21

%S 1,2,3,4,5,6,7,8,9,12,13,14,15,16,17,18,19,23,24,25,26,27,28,29,34,35,

%T 36,37,38,39,45,46,47,48,49,56,57,58,59,67,68,69,78,79,89,120,10,11,

%U 20,21,22,30,31,32,33,40,41,42,43,44,50,51,52,53,54,55,60

%N 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.

%C Computed by _Lars Blomberg_.

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

%H Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/LittleEqualGreat.htm">Less than <, Equal to =, Greater than ></a> (see sequence Ss)

%H Eric Angelini, <a href="/A239083/a239083.pdf">Less than <, Equal to =, Greater than ></a> [Cached copy, with permission of the author]

%t 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,67] (* _Giorgos Kalogeropoulos_, May 13 2022 *)

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

%K nonn,base

%O 1,2

%A _Michel Marcus_, Mar 12 2014