I get 35, can't find 36 and 37.... hmmm
I've found another THREE for you...i see 37.
i suppose there could be 43, but where are the other 6?
D'OH / FAIL / FACEPALM etc etcnope,
those are already included in the top right 6 set (3 external, 3 internal)
D'OH / FAIL / FACEPALM etc etc
But on the upside it suggests my initial 'multiple of six, plus one' theory will be correct.