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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A308748 a(n) is the maximum number of pentagonal polyiamond divisions of an equilateral triangle of order n when tiling with the two smallest pentagonal polyiamonds.

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%I A308748 #41 Apr 14 2020 21:56:21
%S A308748 0,0,0,0,0,0,9,12,15,18,23,28,32,38,44,50,57
%N A308748 a(n) is the maximum number of pentagonal polyiamond divisions of an equilateral triangle of order n when tiling with the two smallest pentagonal polyiamonds.
%C A308748 The two smallest pentagonal polyiamonds contain five and six unit triangles.  All internal angles are either 60, 120 or 240 degrees.
%C A308748 Order five and six equilateral triangle pentagonal tilings require pentagonal tiles larger than hexiamonds.
%H A308748 Craig Knecht, <a href="/A308748/a308748_6.png">Close necks type 1 and type 2.</a>
%H A308748 Craig Knecht, <a href="/A308748/a308748_7.png">Close neck cluster tiling.</a>
%H A308748 Craig Knecht, <a href="/A308748/a308748_8.png">Close neck sphinx tile clusters.</a>
%H A308748 Craig Knecht, <a href="/A308748/a308748.png">Example for the sequence</a>.
%H A308748 Craig Knecht, <a href="/A308748/a308748_2.png">Neck connected pathways</a>.
%H A308748 Craig Knecht, <a href="/A308748/a308748_5.png">Pentagonal tiling of T5, T6</a>.
%H A308748 Craig Knecht, <a href="/A308748/a308748_1.png">Tiling with larger pentagonals</a>.
%H A308748 Walter Trump, <a href="/A259711/a259711_1.pdf">Number of positions of a polyiamond tile in a triangle frame</a>.
%H A308748 Walter Trump, <a href="/A308595/a308595.pdf">Pentagonal polyiamonds</a>.
%Y A308748 Cf. A002061.
%K A308748 nonn,more
%O A308748 1,7
%A A308748 _Craig Knecht_, Jun 21 2019