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

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, 27, 48, 29, 60, 30, 62, 32, 64, 34, 66, 36, 68, 38, 80, 41, 82, 43, 84, 45, 86, 47, 88, 49, 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

Offset: 1

Author

Eric Angelini, Aug 08 2016

Keywords

• nonn
• base

Comments

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.

Examples

			The pair  (1,2)  uses only one odd digit (1);
the pair  (2,3)  uses only one odd digit (3);
the pair  (3,4)  uses only one odd digit (3);
the pair  (4,5)  uses only one odd digit (5);
the pair  (5,6)  uses only one odd digit (5);
the pair  (6,7)  uses only one odd digit (7);
the pair  (7,8)  uses only one odd digit (7);
the pair  (8,9)  uses only one odd digit (9);
the pair  (9,20) uses only one odd digit (9);
the pair (20,10) uses only one odd digit (1);
the pair (10,22) uses only one odd digit (1);
etc.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A014263 (bisection).

Programs

Maple

a:= 0: b:= 0: Res:= NULL:
for i from 1 to 100 do
  for t from a+1 while nops(select(type, convert(t,base,10),odd))<> 1 do
    od;
  a:= t;
  for t from b+1 while nops(select(type,convert(t,base,10),odd))>0 do
    od;
  b:= t;
  Res:= Res, a, b;
od:
Res; # Robert Israel, Nov 03 2017