1–
: 1c lead down the middle and up
9–
: 1c+2c+3c Allemande (3,2,1)
17–
: 3c+2c S&Link ; 3c+1c S&Link (2,1,3) 
25–
: All set | All cross RH ; All chase ½ clw (3,1,2)

{{explanation}}
This unusual progression works both in a 3C and a 4C set.