Skip Spoke Lacing
Wen doing a skip spoke lacing, ie: using a 32 hole rim and hub as a 16, one sides spokes (drive) should be calculated as 32 hole 4 cross, the other side (non-drive) should be calculated as 36 hole 4 cross. This is because the offsets on the hub does not sync correctly with the holes on the rim.
Wikipedia - ISO 5775
Wikipedia - Spokes
Bicycle Wheel Spoke Patterns and Spoke Fatigue
Bicycle Wheel Analysis