# Catalogue of Blunt Polytans

A *polytan* or *polyabolo*
is a figure made of equal isosceles right triangles joined along equal edges.
A *blunt* polytan is one that has no 45° interior angles
(sharp corners).
Here I show all the blunt polytans with up to 9 cells.
*Two-sided* polytans
may be rotated and reflected.
*One-sided* polytans may be rotated but not reflected.

## Enumeration

Cells | Two-Sided A305606 | One-Sided |

1 | 0 | 0 |

2 | 1 | 1 |

3 | 0 | 0 |

4 | 2 | 2 |

5 | 2 | 2 |

6 | 5 | 6 |

7 | 6 | 10 |

8 | 23 | 38 |

9 | 45 | 84 |

10 | 138 | 252 |

11 | 347 | 675 |

12 | 1007 | 1954 |

13 | 2751 | 5455 |

14 | 7998 | 15829 |

The enumerations for arbitrary polyaboloes are in the On-Line Encyclopedia
of Integer Sequences as A006074
(two-sided) and
A151519 (one-sided).

The figures below show two-sided polytans.

## Ditans

## Tetratans

## Pentatans

## Hexatans

## Heptatans

## Octatans

## Enneatans

Last revised 2017-11-25.

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Col. George Sicherman
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