Place two n-gons with radii 1 and 2 concentrically, forming an annular area between them. Connect all the vertices with line segments that lie entirely within that area. Then a(n) is the number of regions in that figure.

A337700

Place two n-gons with radii 1 and 2 concentrically, forming an annular area between them. Connect all the vertices with line segments that lie entirely within that area. Then a(n) is the number of regions in that figure.

Terms

    a(0) =12a(1) =16a(2) =20a(3) =24a(4) =63a(5) =72a(6) =315a(7) =350a(8) =385a(9) =408a(10) =767a(11) =826a(12) =2085a(13) =2224a(14) =2363a(15) =2340a(16) =3762a(17) =3960a(18) =7644a(19) =8008a(20) =8372a(21) =8448a(22) =11850a(23) =12324a(24) =20466a(25) =21224a(26) =21982a(27) =21480a(28) =28985a(29) =29920

External references