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A275775 The pair (a(n), a(n+1)) uses only one odd digit. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A247227 A048410 A180083 * A217556 A249873 A102491

Adjacent sequences:  A275772 A275773 A275774 * A275776 A275777 A275778

KEYWORD

nonn,base

AUTHOR

Eric Angelini, Aug 08 2016

STATUS

approved

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Last modified February 27 22:32 EST 2020. Contains 332312 sequences. (Running on oeis4.)