A289137 - OEIS

A289137

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

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..7.

Bernd Karl Rennhak, Logelium: Drafter

EXAMPLE

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

See the Logelium link for diagrams.

CROSSREFS

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

Sequence in context: A348024 A000836 A157771 * A228481 A277512 A141878

Adjacent sequences: A289134 A289135 A289136 * A289138 A289139 A289140

KEYWORD

nonn,more,hard

AUTHOR

George Sicherman, Jun 25 2017

STATUS

approved