Acronym	stoap, 8/3-ap
Name	octagrammic antiprism
	©
Circumradius	sqrt[(3-sqrt{2-sqrt(2)})/(8-4 sqrt{2-sqrt(2)})] = 0.672673
Vertex figure	[33,8/3]
General of army	(is itself convex)
Colonel of regiment	(is itself locally convex)
Dihedral angles	between {3} and {8/3}:   arccos(-sqrt[(2-sqrt(2-sqrt(2)))/(6+3 sqrt(2-sqrt(2)))]) = 112.691745° between {3} and {3}:   arccos([1-2 sqrt(2-sqrt(2))]/3) = 100.189900°
Face vector	16, 32, 18
Confer	more general: nd-ap   general polytopal classes: segmentohedra
External links

As abstract polytope stoap is isomorphic to oap, thereby replacing octagrams by octagons.

Incidence matrix according to Dynkin symbol

s2s8/3s

demi( . .   .  ) | 16 | 1 1  2 | 1  3
-----------------+----+--------+-----
      s2s   .    |  2 | 8 *  * | 0  2
      s .   s2*a |  2 | * 8  * | 0  2
sefa( . s8/3s  ) |  2 | * * 16 | 1  1
-----------------+----+--------+-----
      . s8/3s    ♦  8 | 0 0  8 | 2  *
sefa( s2s8/3s  ) |  3 | 1 1  1 | * 16

s2s16/3o

demi( . .    . ) | 16 |  2  2 | 1  3
-----------------+----+-------+-----
      s2s    .   |  2 | 16  * | 0  2
sefa( . s16/3o ) |  2 |  * 16 | 1  1
-----------------+----+-------+-----
      . s16/3o   ♦  8 |  0  8 | 2  *
sefa( s2s16/3o ) |  3 |  2  1 | * 16

xo8/3ox&#x   → height = sqrt[(1+sqrt(2-sqrt(2)))/(2+sqrt(2-sqrt(2)))] = 0.798990
({8/3} || dual {8/3})

o.8/3o.    | 8 * | 2  2 0 | 1 2 1 0
.o8/3.o    | * 8 | 0  2 2 | 0 1 2 1
-----------+-----+--------+--------
x.   ..    | 2 0 | 8  * * | 1 1 0 0
oo8/3oo&#x | 1 1 | * 16 * | 0 1 1 0
..   .x    | 0 2 | *  * 8 | 0 0 1 1
-----------+-----+--------+--------
x.8/3o.    | 8 0 | 8  0 0 | 1 * * *
xo   ..&#x | 2 1 | 1  2 0 | * 8 * *
..   ox&#x | 1 2 | 0  2 1 | * * 8 *
.o8/3.x    | 0 8 | 0  0 8 | * * * 1