cp's OEIS Frontend

A239215 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.

%I A239215 #17 Jul 31 2022 07:44:03
%S A239215 1,2,3,4,5,6,7,8,9,11,12,13,14,15,16,17,18,19,22,23,24,25,26,27,28,29,
%T A239215 33,34,35,36,37,38,39,44,45,46,47,48,49,55,56,57,58,59,66,67,68,69,77,
%U A239215 78,79,88,89,99,999,9999,99999,999999,9999999,99999999
%N A239215 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 A239215 Computed by _Lars Blomberg_.
%D A239215 Eric Angelini, Posting to Sequence Fans Mailing List, Sep 28 2013
%H A239215 Eric Angelini, <a href="http://www.cetteadressecomportecinquantesignes.com/LittleEqualGreat.htm">Less than <, Equal to =, Greater than ></a> (see sequence Sr)
%H A239215 Eric Angelini, <a href="/A239083/a239083.pdf">Less than <, Equal to =, Greater than ></a> [Cached copy, with permission of the author]
%t A239215 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,56] (* _Giorgos Kalogeropoulos_, May 13 2022 *)
%Y A239215 The sequences in this family are given in A239083-A239086, A239136-A239139, A239087-A239090, A239215-A239218, A239235.
%K A239215 nonn,base
%O A239215 1,2
%A A239215 _Michel Marcus_, Mar 12 2014