Acronym n/d,2n/d-dip
Name n/d-gram - 2n/d-gram duoprism
Circumradius sqrt[1/(4 sin2(π d/n))+1/(4 sin2(π d/2n))]
Especially
Confer
more general:
n/d,m/b-dip   2n,m-dip (d=b=1)
External

Incidence matrix according to Dynkin symbol

```x-n/d-o x-2n/d-o   (n>2, d odd, n and d divisor free)

.     . .      . | 2nn |   2   2 |  1   4 1 |  2 2
-----------------+-----+---------+----------+-----
x     . .      . |   2 | 2nn   * |  1   2 0 |  2 1
.     . x      . |   2 |   * 2nn |  0   2 1 |  1 2
-----------------+-----+---------+----------+-----
x-n/d-o .      . |   n |   n   0 | 2n   * * |  2 0
x     . x      . |   4 |   2   2 |  * 2nn * |  1 1
.     . x-2n/d-o |  2n |   0  2n |  *   * n |  0 2
-----------------+-----+---------+----------+-----
x-n/d-o x      . ♦  2n |  2n   n |  2   n 0 | 2n *
x     . x-2n/d-o ♦  4n |  2n  4n |  0  2n 2 |  * n
```

```x-n/d-o x-n/d-x   (n>2, d odd, gcd(n,d)=1)

.     . .     . | 2nn |   2  1  1 |  1  2  2 1 | 1 1 2
----------------+-----+-----------+------------+------
x     . .     . |   2 | 2nn  *  * |  1  1  1 0 | 1 1 1
.     . x     . |   2 |   * nn  * |  0  2  0 1 | 1 0 2
.     . .     x |   2 |   *  * nn |  0  0  2 1 | 0 1 2
----------------+-----+-----------+------------+------
x-n/d-o .     . |   n |   n  0  0 | 2n  *  * * | 1 1 0
x     . x     . |   4 |   2  2  0 |  * nn  * * | 1 0 1
x     . .     x |   4 |   2  0  2 |  *  * nn * | 0 1 1
.     . x-n/d-x |  2n |   0  n  n |  *  *  * n | 0 0 2
----------------+-----+-----------+------------+------
x-n/d-o x     . ♦  2n |  2n  n  0 |  2  n  0 0 | n * *
x-n/d-o .     x ♦  2n |  2n  0  n |  2  0  n 0 | * n *
x     . x-n/d-x ♦  4n |  2n 2n 2n |  0  n  n 2 | * * n
```