A tri-oddity is an arrangement of copies of a polyform with ternary rotary symmetry or better, using a number of copies that is not a multiple of 3.
Here I show the smallest known tri-oddities with horizontal mirror symmetry that can be formed by copies of two heptiamonds, using at least one of each. If you find a smaller solution, or solve an unsolved pair, please write.
See also
| AB 22 | AC 19 | AD 19 | AE 13 | AF 19 | AG 46 |
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| AH 13 | AI 34 | AJ ? | AK 7 | AL 19 | AM ? |
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| AN 22 | AP 16 | AQ 22 | AR 22 | AS 10 | AT ? |
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| AU 61 | AV ? | AX 13 | AY 13 | AZ 40 | BC 19 |
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| BD 16 | BE 16 | BF 16 | BG 16 | BH 22 | BI 13 |
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| BJ 19 | BK 10 | BL 19 | BM 19 | BN 16 | BP 19 |
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| BQ 22 | BR 22 | BS 22 | BT 22 | BU 19 | BV 19 |
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| BX 16 | BY 13 | BZ 19 | CD 10 | CE 13 | CF 13 |
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| CG 19 | CH 22 | CI 16 | CJ 16 | CK 13 | CL 13 |
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| CM 22 | CN 22 | CP 19 | CQ 19 | CR 16 | CS 16 |
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| CT 10 | CU 46 | CV 67 | CX 7 | CY 13 | CZ 19 |
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| DE 16 | DF 13 | DG 19 | DH 13 | DI 10 | DJ ? |
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| DK 13 | DL 10 | DM 19 | DN 16 | DP 19 | DQ 4 |
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| DR 10 | DS 10 | DT 10 | DU 10 | DV ? | DX 10 |
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| DY 10 | DZ 10 | EF 28 | EG 13 | EH 13 | EI 19 |
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| EJ 16 | EK 10 | EL 19 | EM 43 | EN 28 | EP 16 |
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| EQ 40 | ER 13 | ES 13 | ET 16 | EU 16 | EV 40 |
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| EX 10 | EY 7 | EZ 22 | FG 22 | FH 16 | FI 25 |
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| FJ 34 | FK 10 | FL 25 | FM 40 | FN 22 | FP 16 |
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| FQ 25 | FR 22 | FS 10 | FT ? | FU ? | FV ? |
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| FX 7 | FY 13 | FZ 22 | GH 25 | GI 19 | GJ ? |
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| GK 13 | GL 13 | GM 22 | GN 19 | GP 40 | GQ 22 |
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| GR 19 | GS 16 | GT 46 | GU 28 | GV ? | GX 10 |
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| GY 13 | GZ 22 | HI 22 | HJ 22 | HK 13 | HL 22 |
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| HM 40 | HN 22 | HP 16 | HQ 40 | HR 16 | HS 13 |
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| HT 13 | HU 22 | HV 40 | HX 4 | HY 10 | HZ 19 |
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| IJ 28 | IK 10 | IL 13 | IM 13 | IN 22 | IP 28 |
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| IQ 19 | IR 19 | IS 7 | IT 28 | IU ? | IV 25 |
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| IX 13 | IY 10 | IZ 28 | JK 13 | JL 16 | JM ? |
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| JN 16 | JP 10 | JQ 25 | JR 16 | JS 7 | JT 16 |
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| JU ? | JV ? | JX 7 | JY 13 | JZ ? | KL 7 |
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| KM 13 | KN 10 | KP 7 | KQ 10 | KR 13 | KS 13 |
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| KT 7 | KU 10 | KV 13 | KX 4 | KY 4 | KZ 10 |
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| LM 16 | LN 16 | LP 52 | LQ 34 | LR 16 | LS 16 |
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| LT ? | LU 16 | LV ? | LX 10 | LY 10 | LZ 52 |
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| MN 13 | MP ? | MQ ? | MR 28 | MS 19 | MT ? |
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| MU ? | MV ? | MX 22 | MY 10 | MZ ? | NP 22 |
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| NQ 28 | NR 16 | NS 16 | NT ? | NU ? | NV 28 |
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| NX 7 | NY 13 | NZ 16 | PQ 13 | PR 28 | PS 16 |
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| PT 19 | PU 16 | PV ? | PX 7 | PY 10 | PZ 19 |
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| QR 16 | QS 13 | QT 19 | QU 13 | QV ? | QX 4 |
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| QY 13 | QZ 25 | RS 16 | RT 25 | RU 43 | RV 25 |
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| RX 10 | RY 19 | RZ 25 | ST 19 | SU 13 | SV 19 |
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| SX 13 | SY 10 | SZ 7 | TU ? | TV ? | TX 7 |
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| TY 7 | TZ 22 | UV ? | UX 16 | UY 10 | UZ 34 |
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| VX 22 | VY 10 | VZ ? | XY 4 | XZ 7 | YZ 13 |
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Last revised 2025-02-23.