A289137 - OEIS

%I #8 Jul 03 2017 22:34:19

%S 1,13,88,1025,11822,147003,1866907

%N Number of extended polydrafters with n cells, identifying mirror images.

%C An extended polydrafter is a plane figure formed by joining congruent 30-60-90 triangles along edges and half hypotenuses, without the requirement for proper polydrafters that the cells lie on the polyiamond (triangle) grid.

%H Bernd Karl Rennhak, <a href="http://www.logelium.de/Drafter/PolyDrafter_EN.htm">Logelium: Drafter</a>

%e a(2)=13 because there are 6 proper didrafters and 7 more didrafters that do not conform to the polyiamond grid.

%e See the Logelium link for diagrams.

%Y Cf. A056842 (number of [proper] polydrafters with n cells); A217720 (number of one-sided polydrafters with n cells).

%K nonn,more,hard

%O 1,2

%A _George Sicherman_, Jun 25 2017