Illustration for the tootkpick sequence A139250.

A vertical toothpick is represented as
|

|
A horizontal toothpick is represented as
- -
Note in each case the space between the two dashes.
Therefore - - - - represents two adjacent toothpicks.


a(0) = 0


a(1) = 1
|

|


a(2) = 3
- -
 |

 |
- -


a(3) = 7
|   |
 - -
| | |

| | |
 - -
|   |


a(4) = 11
- - - -
 |   |
  - -
 | | |

 | | |
  - -
 |   |
- - - -


a(5) = 15
|       |
 - - - -
| |   | |
   - -
  | | |

  | | |
   - -
| |   | |
 - - - -
|       |


a(6) = 23
- -     - -
 |       |
  - - - -
 | |   | |
- - - - - -
   | | |

   | | |
- - - - - -
 | |   | |
  - - - -
 |       |
- -     - -


a(7) = 35
|   |   |   |
 - -     - -
| | |   | | |
   - - - -
| | |   | | |
 - - - - - -
|   | | |   |

|   | | |   |
 - - - - - -
| | |   | | |
   - - - -
| | |   | | |
 - -     - -
|   |   |   |


a(8) = 43
- - - - - - - -
 |   |   |   |
  - -     - -
 | | |   | | |
    - - - -
 | | |   | | |
  - - - - - -
 |   | | |   |

 |   | | |   |
  - - - - - -
 | | |   | | |
    - - - -
 | | |   | | |
  - -     - -
 |   |   |   |
- - - - - - - -


a(9) = 47
|               |
 - - - - - - - -
| |   |   |   | |
   - -     - -
  | | |   | | |
     - - - -
  | | |   | | |
   - - - - - -
  |   | | |   |

  |   | | |   |
   - - - - - -
  | | |   | | |
     - - - -
  | | |   | | |
   - -     - -
| |   |   |   | |
 - - - - - - - -
|               |