cp's OEIS Frontend

A275775 The pair (a(n), a(n+1)) uses only one odd digit.

%I A275775 #12 Nov 04 2017 01:13:07
%S A275775 1,2,3,4,5,6,7,8,9,20,10,22,12,24,14,26,16,28,18,40,21,42,23,44,25,46,
%T A275775 27,48,29,60,30,62,32,64,34,66,36,68,38,80,41,82,43,84,45,86,47,88,49,
%U A275775 200,50,202,52,204,54,206,56,208,58,220,61,222,63,224,65,226,67,228,69,240,70,242,72,244,74,246,76,248,78,260,81,262,83,264,85,266,87,268
%N A275775 The pair (a(n), a(n+1)) uses only one odd digit.
%C A275775 The sequence starts with a(1) = 1 and is always extended with the smallest integer not yet used that doesn't lead to a contradiction.
%H A275775 Robert Israel, <a href="/A275775/b275775.txt">Table of n, a(n) for n = 1..10000</a>
%e A275775 The pair  (1,2)  uses only one odd digit (1);
%e A275775 the pair  (2,3)  uses only one odd digit (3);
%e A275775 the pair  (3,4)  uses only one odd digit (3);
%e A275775 the pair  (4,5)  uses only one odd digit (5);
%e A275775 the pair  (5,6)  uses only one odd digit (5);
%e A275775 the pair  (6,7)  uses only one odd digit (7);
%e A275775 the pair  (7,8)  uses only one odd digit (7);
%e A275775 the pair  (8,9)  uses only one odd digit (9);
%e A275775 the pair  (9,20) uses only one odd digit (9);
%e A275775 the pair (20,10) uses only one odd digit (1);
%e A275775 the pair (10,22) uses only one odd digit (1);
%e A275775 etc.
%p A275775 a:= 0: b:= 0: Res:= NULL:
%p A275775 for i from 1 to 100 do
%p A275775   for t from a+1 while nops(select(type, convert(t,base,10),odd))<> 1 do
%p A275775     od;
%p A275775   a:= t;
%p A275775   for t from b+1 while nops(select(type,convert(t,base,10),odd))>0 do
%p A275775     od;
%p A275775   b:= t;
%p A275775   Res:= Res, a, b;
%p A275775 od:
%p A275775 Res; # _Robert Israel_, Nov 03 2017
%Y A275775 Cf. A014263 (bisection).
%K A275775 nonn,base
%O A275775 1,2
%A A275775 _Eric Angelini_, Aug 08 2016