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a(0) = 4 from the complete graph K_4.
a(1) = 6 from the utility graph K_{3,3}.
a(2) = 10 from the Petersen graph (and 1 other).
a(3) = 14 from the Heawood graph (and 7 others).
a(4) = 16 from the Moebius-Kantor graph (and 1 other).
a(5) = 18 from the Pappus graph (and 1 other).
a(6) = 20 from the Desargues graph (and 2 others based on 10_3 configurations).
a(7) = 22 from the 7-crossing graphs (4 in total).
a(8) = 24 from the McGee graph (and 3 others).
a(9) = 26 from the McGee graph + edge insertion and edge-excised Coxeter graph (and unknown others).
a(10) = 28 from the McGee graph + double edge insertion and another from Clancy et al. preprint (and unknown others).
a(11) = 28 from the Coxeter graph (and unknown others).
a(12) <= 30 from the CNG 10A + edge insertion.
a(13) <= 30 from the Levi graph.
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