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

1,2

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.

Links

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

Example

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.

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

Crossrefs

Cf. A014263 (bisection).

Sequence in context: A341161 A180083 A345142 * A358129 A217556 A249873

Adjacent sequences: A275772 A275773 A275774 * A275776 A275777 A275778

Keyword

nonn,base

Author

Eric Angelini, Aug 08 2016

Status

approved