(1/4)(3/4)(1/2)*(3/4)(1/4)(1/4)[(1/4)(3/4)(1/4)+(3/4)(1/4)**]

* can be R or D
** last can be anything

= 135/131072
= ~971:1 true odds

[(3/4)(1/4)**]

= 27/32768
= ~1214:1 actual odds